Matt Walker: Sleep
生物与进化心理与人性音乐与艺术哲学与宗教技术与编程
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sleepdonbraindoingdreamcallednightsaidconsciousnessgoinghumancoffeeconsciousbedcaffeinewaysawakestategotsleeping
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🎙️ 完整对话（3465 条）
Lex Fridman (00:00.000)
The following is a conversation with Matt Walker,
以下是与马特·沃克的对话，
Lex Fridman (00:02.520)
sleep scientist, professor of neuroscience
睡眠科学家、神经科学教授
Lex Fridman (00:04.840)
and psychology at Berkeley, author of Why We Sleep,
伯克利大学心理学教授，《我们为什么睡觉》一书的作者，
Lex Fridman (00:08.680)
and the host of a new podcast called The Matt Walker Podcast.
以及一个名为“马特·沃克播客”的新播客的主持人。
Lex Fridman (00:14.240)
It's 10 minute episodes a couple of times a month,
每个月都会有几次 10 分钟的剧集
Matt Walker (00:17.140)
covering sleep and other health and science topics.
涵盖睡眠以及其他健康和科学主题。
Lex Fridman (00:20.760)
I love it and recommend it highly.
我喜欢它并强烈推荐它。
Matt Walker (00:22.560)
It's up there with the greats,
与伟人齐名，
Lex Fridman (00:24.400)
like the Huberman Lab Podcast with Andrew Huberman,
就像安德鲁·胡伯曼的胡伯曼实验室播客，
Lex Fridman (00:28.080)
and I think David Sinclair is putting out
我认为大卫·辛克莱正在推出
Lex Fridman (00:30.600)
an audio series soon too.
音频系列也很快。
Matt Walker (00:32.320)
I can't wait to listen to it.
我迫不及待地想听。
Lex Fridman (00:33.760)
I'm really excited by the future of science
我对科学的未来感到非常兴奋
Matt Walker (00:36.800)
in the podcasting world.
在播客世界中。
Lex Fridman (00:38.680)
To support this podcast, please check out our sponsors,
为了支持这个播客，请查看我们的赞助商，
Matt Walker (00:41.680)
Stamps.com, Squarespace, Athletic Greens,
Stamps.com、Squarespace、运动绿地、
Lex Fridman (00:45.280)
BetterHelp, and Onnit.
Matt Walker (00:47.160)
Their links are in the description.
他们的链接在描述中。
Lex Fridman (00:49.840)
As a side note, let me say that to me,
作为旁注，让我对我说，
Matt Walker (00:52.240)
a healthy life is one in which you fall in love
健康的生活就是你坠入爱河的生活
Lex Fridman (00:55.120)
with the world around you, with ideas, with people,
Matt Walker (00:58.640)
with small goals and big goals, no matter how difficult,
Lex Fridman (01:02.080)
with dreams you hold onto and chase for years.
Matt Walker (01:05.880)
Life should be lived fully.
Lex Fridman (01:07.940)
That, to me, is the priority.
Matt Walker (01:10.000)
That, to me, is a healthy life.
Lex Fridman (01:12.080)
Second to that is the understanding and the utilization
Matt Walker (01:15.520)
of the best available science on diet, exercise,
Lex Fridman (01:18.600)
supplements, sleep, and other lifestyle choices.
Matt Walker (01:22.740)
To me, science in the realm of health is a guide
Lex Fridman (01:26.520)
for what we should try, not the absolute truth
Matt Walker (01:28.960)
of how to live life.
Lex Fridman (01:30.960)
The goal is to learn to listen to your body
Lex Fridman (01:33.040)
and figure out what works best for you.
Lex Fridman (01:35.800)
All that said, a good night's sleep can be a great tool
Matt Walker (01:39.480)
in making life awesome and productive,
Lex Fridman (01:41.720)
and Matt is a great advocate of the how and the why of sleep.
Matt Walker (01:46.960)
We agree on some things and disagree on others,
Lex Fridman (01:49.760)
but he's a great human being, a great scientist,
Matt Walker (01:52.440)
and, as of recently, a friend with whom I enjoy
Lex Fridman (01:55.480)
having these wide ranging conversations.
Matt Walker (01:58.680)
This is the Lux Friedman podcast,
Lex Fridman (02:00.840)
and here is my conversation with Matt Walker.
Matt Walker (02:05.080)
You should try these shades on.
Lex Fridman (02:06.480)
Let's see what you look like.
Lex Fridman (02:11.160)
So they are now your shades, and that's not the question.
Lex Fridman (02:14.720)
It's the same thing as Putin took the Super Bowl ring,
Lex Fridman (02:17.680)
and it's now his ring.
Lex Fridman (02:18.860)
Yeah, one wonders if he was offered it,
Lex Fridman (02:22.620)
but they are yours.
Lex Fridman (02:26.380)
When did you first fall in love with the dream
Lex Fridman (02:31.500)
of understanding sleep?
Lex Fridman (02:32.820)
Like, where did the fascination with sleep begin?
Lex Fridman (02:38.420)
So back in the United Kingdom,
Lex Fridman (02:41.060)
you can sort of start doing medicine at age 18,
Lex Fridman (02:44.060)
and it's a five year program,
Lex Fridman (02:46.020)
and I was at the Queen's Medical Center in the UK,
Lex Fridman (02:50.620)
and I remember just being fascinated
Lex Fridman (02:52.740)
by states of consciousness, and particularly anesthesia.
Matt Walker (02:57.180)
I was thinking, isn't that, within seconds,
Lex Fridman (03:00.220)
I can take a perfectly conscious human being,
Lex Fridman (03:03.300)
and I can remove all existence of the mentality
Lex Fridman (03:07.540)
and their awareness within seconds,
Lex Fridman (03:10.700)
and that stunned me.
Lex Fridman (03:12.500)
So I started to get really interested in conscious states.
Matt Walker (03:15.500)
I even started to read a lot about hypnosis,
Lex Fridman (03:19.700)
and all of these things, hypnosis,
Matt Walker (03:22.280)
even sleep and dreams at the time,
Lex Fridman (03:24.340)
they were very esoteric.
Matt Walker (03:25.940)
It was sort of charlatan science at that stage,
Lex Fridman (03:29.720)
and I think almost all of my colleagues and I
Matt Walker (03:33.660)
are accidental sleep researchers.
Lex Fridman (03:36.660)
No one, as I recall, in the classroom
Matt Walker (03:38.980)
when you're sort of five years old,
Lex Fridman (03:40.340)
and the teacher says,
Lex Fridman (03:41.340)
what would you like to be when you grow up?
Lex Fridman (03:44.020)
No one's putting their hand up and saying,
Matt Walker (03:45.340)
I would love to be a sleep researcher.
Lex Fridman (03:48.540)
And so when I was doing my PhD,
Matt Walker (03:51.500)
I was trying to identify different forms of dementia
Lex Fridman (03:55.060)
very early on in the course,
Lex Fridman (03:57.500)
and I was using electrical brainwave recordings to do that,
Lex Fridman (04:00.660)
and I was failing miserably.
Matt Walker (04:02.620)
It was a disaster, just no result after no result.
Lex Fridman (04:07.260)
And I used to go home to the doctor's residence
Matt Walker (04:09.220)
with this sort of little igloo of journals
Lex Fridman (04:11.260)
that at the weekend I would sort of sit in and read,
Lex Fridman (04:15.060)
and which I'm now thinking,
Lex Fridman (04:16.940)
do I really want to admit this?
Matt Walker (04:18.140)
Because it sounds like I had no social life,
Lex Fridman (04:19.780)
which I didn't, I was a social leper.
Matt Walker (04:21.900)
But, and I started to realize that some parts of the brain
Lex Fridman (04:26.260)
were sleep related areas,
Lex Fridman (04:29.020)
and some dementias were eating away
Lex Fridman (04:31.540)
those sleep related areas.
Matt Walker (04:33.660)
Other dementias would leave them untouched.
Lex Fridman (04:35.780)
And I thought, well, I'm doing this all wrong.
Matt Walker (04:38.060)
I'm measuring my patients while they're awake.
Lex Fridman (04:41.260)
Instead, I should be measuring them while they're asleep.
Matt Walker (04:43.980)
Started doing that, got some amazing results.
Lex Fridman (04:47.500)
And then I wanted to ask the question,
Matt Walker (04:49.700)
is that sleep disruption that my patients are experiencing
Lex Fridman (04:54.100)
as they go into dementia,
Matt Walker (04:55.700)
maybe it's not a symptom of the dementia.
Lex Fridman (04:57.900)
I wonder if it's a cause of the dementia.
Lex Fridman (05:01.940)
And at that point, which was, cough, cough, 20 years ago,
Lex Fridman (05:07.820)
no one could answer a very simple fundamental question.
Lex Fridman (05:11.060)
Why do we sleep?
Lex Fridman (05:12.020)
And I at the time didn't realize
Matt Walker (05:17.020)
that some of the most brilliant minds in scientific history
Lex Fridman (05:19.820)
had tried to answer that question and failed.
Lex Fridman (05:22.580)
And at that point, I just thought, well,
Lex Fridman (05:24.540)
I'm going to go and do a couple of years of sleep research
Lex Fridman (05:27.660)
and I'll figure out why we sleep.
Lex Fridman (05:30.220)
And then I'll come back to my patients
Matt Walker (05:31.700)
in this question of dementia.
Lex Fridman (05:33.700)
And as I said, that was 20 years ago.
Lex Fridman (05:35.420)
And what I realized is that hard questions
Lex Fridman (05:38.620)
care very little about who asks them.
Matt Walker (05:41.460)
They will meter out their lessons of difficulty
Lex Fridman (05:44.060)
all the same.
Lex Fridman (05:45.180)
And I was schooled in the difficulty of the question,
Lex Fridman (05:48.860)
why do we sleep?
Lex Fridman (05:50.540)
But in truth, 20 years later,
Lex Fridman (05:53.020)
we've had to upend the question
Lex Fridman (05:55.300)
rather than saying, why do we sleep?
Lex Fridman (05:57.260)
And by the way, the answer then was
Matt Walker (05:59.980)
that we sleep to cure sleepiness,
Lex Fridman (06:03.580)
which is like saying, we eat to cure hunger.
Matt Walker (06:07.060)
That tells you nothing about the physiological benefits
Lex Fridman (06:09.380)
of food, same with sleep.
Matt Walker (06:11.580)
Now we've actually have to ask the question,
Lex Fridman (06:14.300)
is there any physiological system in the body
Matt Walker (06:17.100)
or any major operation of the mind
Lex Fridman (06:19.340)
that isn't wonderfully enhanced when we get sleep
Lex Fridman (06:22.380)
or demonstrably impaired when we don't get enough?
Lex Fridman (06:25.580)
And so far, for the most part, the answer seems to be no.
Lex Fridman (06:29.940)
So far, the answer seems to be no.
Lex Fridman (06:32.940)
So why does the body and the mind crave sleep?
Lex Fridman (06:37.940)
Crave sleep then?
Lex Fridman (06:39.700)
Why do we sleep?
Lex Fridman (06:41.140)
How can we begin to answer that question then?
Lex Fridman (06:45.780)
So I think one of the ways that I think about this
Matt Walker (06:48.220)
or one of the answers that came to me is the following.
Lex Fridman (06:53.060)
The reason that we implode so quickly
Lex Fridman (06:55.460)
and so thoroughly with insufficient sleep
Lex Fridman (06:58.660)
is because human beings seem to be one of the few species
Matt Walker (07:01.780)
that will deliberately deprive themselves of sleep
Lex Fridman (07:04.020)
for no apparent good reason, biological.
Lex Fridman (07:06.700)
And what that led me then to was the following.
Lex Fridman (07:11.380)
Mother nature as a consequence.
Lex Fridman (07:13.580)
So no other species does what we do in that context.
Lex Fridman (07:17.780)
There are a few species that do undergo sleep deprivation,
Lex Fridman (07:20.940)
but for very obvious, clear biological reasons.
Lex Fridman (07:24.500)
One is when they're in a condition of severe starvation.
Matt Walker (07:27.620)
The second is when they're caring for their newborn.
Lex Fridman (07:30.900)
So for example, killer whales will often deprive themselves.
Matt Walker (07:34.180)
The female will go away from the pod, give birth,
Lex Fridman (07:37.780)
and then bring the calf back.
Lex Fridman (07:39.860)
And during that time,
Lex Fridman (07:41.260)
the mother will undergo sleep deprivation.
Lex Fridman (07:43.980)
And then the third one is during migration
Lex Fridman (07:46.580)
when birds are flying trans oceanographic 2,000, 3,000 miles.
Lex Fridman (07:51.380)
But for the most part,
Lex Fridman (07:52.340)
it's never seen in the animal kingdom,
Matt Walker (07:54.980)
which brings me back to the point,
Lex Fridman (07:57.140)
therefore mother nature in the course of evolution
Matt Walker (08:00.900)
has never had to face the challenge of this thing
Lex Fridman (08:03.540)
called sleep deprivation.
Lex Fridman (08:05.940)
And therefore she has never created a safety net in place
Lex Fridman (08:11.300)
to circumnavigate this common influence.
Lex Fridman (08:15.300)
And there is a good example where we have,
Lex Fridman (08:18.420)
which is called the adipose cell, the fat cell.
Matt Walker (08:22.300)
Because during our evolutionary past,
Lex Fridman (08:24.420)
we had famine and we had feast.
Lex Fridman (08:26.860)
And mother nature came up with a very clever recipe,
Lex Fridman (08:29.140)
which is how can I store caloric credit
Lex Fridman (08:34.460)
so that I can spend it when I go into debt?
Lex Fridman (08:37.220)
And the fat cell was born, brilliant idea.
Lex Fridman (08:39.620)
Where is the fat cell for sleep?
Lex Fridman (08:42.020)
Where is that sort of banking chip for sleep?
Lex Fridman (08:44.380)
And unfortunately we don't seem to have one
Lex Fridman (08:46.580)
because she's never had to face that challenge.
Lex Fridman (08:49.380)
So even if there's not some kind of physics,
Lex Fridman (08:52.660)
fundamental need for sleep
Matt Walker (08:55.300)
that physiologically or psychologically,
Lex Fridman (08:58.820)
the fact is most organisms are built such that they need it.
Lex Fridman (09:03.820)
And then mother nature never built an extra mechanism
Lex Fridman (09:08.060)
for sleep deprivation.
Lex Fridman (09:09.580)
So it's interesting that why we sleep
Lex Fridman (09:12.180)
might not have a good answer,
Lex Fridman (09:14.940)
but we need to sleep to be healthy is nevertheless true.
Lex Fridman (09:19.460)
Yeah, and we have many answers right now.
Matt Walker (09:21.700)
In some ways the question of why we sleep
Lex Fridman (09:23.940)
was the wrong question too.
Lex Fridman (09:25.940)
It's what are the plory potent many reasons we sleep?
Lex Fridman (09:30.220)
We don't just sleep for one reason
Matt Walker (09:32.500)
because from an evolutionary perspective,
Lex Fridman (09:35.740)
it is the most idiotic thing that you could imagine.
Matt Walker (09:39.940)
When you're sleeping, you're not finding a mate,
Lex Fridman (09:42.980)
you're not reproducing,
Matt Walker (09:43.900)
you're not caring for your young,
Lex Fridman (09:45.500)
you're not foraging for food,
Lex Fridman (09:47.420)
and worse still, you're vulnerable to predation.
Lex Fridman (09:50.580)
So on any one of those grounds,
Matt Walker (09:52.700)
especially as a collective,
Lex Fridman (09:54.660)
sleep should have been strongly selected against
Matt Walker (09:57.860)
in the course of evolution.
Lex Fridman (09:59.780)
But in every species that we've studied carefully to date,
Matt Walker (10:03.900)
sleep is present.
Lex Fridman (10:05.660)
Yeah, so it is important.
Lex Fridman (10:07.060)
So like you're right.
Lex Fridman (10:09.020)
I think I've heard arguments
Matt Walker (10:10.380)
from an evolutionary biology perspective
Lex Fridman (10:12.260)
that sleep is actually advantageous,
Matt Walker (10:15.780)
maybe like some kind of predator prey relationships.
Lex Fridman (10:18.580)
But you're saying,
Lex Fridman (10:19.860)
and it actually makes way more sense what you're saying
Lex Fridman (10:22.500)
is it should have been selected against.
Lex Fridman (10:25.180)
Like why close your eyes?
Lex Fridman (10:27.300)
Yeah, why?
Matt Walker (10:28.140)
Because there was an energy conservation hypothesis
Lex Fridman (10:31.900)
for a while,
Matt Walker (10:32.740)
which is that we need to essentially go
Lex Fridman (10:34.140)
into low battery mode, power down,
Matt Walker (10:37.380)
because it's unsustainable.
Lex Fridman (10:38.860)
But in fact, that actually has been blasted out the water
Matt Walker (10:41.900)
because sleep is an incredibly active process.
Lex Fridman (10:45.660)
In fact, the difference between you just lying on the couch
Lex Fridman (10:48.900)
but remaining conscious versus you lying on the couch
Lex Fridman (10:51.820)
and falling asleep,
Matt Walker (10:53.060)
it's only a savings of about 140, 150 calories.
Lex Fridman (10:56.660)
In other words, you just go out
Lex Fridman (10:58.540)
and club another baby seal or whatever it was,
Lex Fridman (11:00.940)
and you wouldn't worry.
Lex Fridman (11:02.380)
So it has to be much more to it than energy conservation,
Lex Fridman (11:05.060)
much more to it than sharing ecosystem space and time,
Matt Walker (11:09.780)
much more to it than simply predator prey relationships.
Lex Fridman (11:13.620)
If sleep really did,
Lex Fridman (11:15.220)
and looking back,
Lex Fridman (11:17.260)
even very old evolutionary organisms like earthworms,
Matt Walker (11:20.740)
millions of years old,
Lex Fridman (11:22.100)
they have periods where they're active
Lex Fridman (11:24.740)
and periods where they're passively asleep.
Lex Fridman (11:26.500)
It's called lethargicus.
Lex Fridman (11:28.700)
And so what that in some ways suggested to me
Lex Fridman (11:32.180)
was sleep evolved with life itself on this planet,
Lex Fridman (11:36.660)
and then it has fought its way through heroically
Lex Fridman (11:39.660)
every step along the evolutionary pathway,
Matt Walker (11:42.620)
which then leads to the sort of famous sleep statement
Lex Fridman (11:46.540)
from a researcher that if sleep doesn't serve
Matt Walker (11:48.860)
an absolutely vital function or functions,
Lex Fridman (11:52.180)
then it's the biggest mistake
Matt Walker (11:53.220)
the evolutionary process has ever made.
Lex Fridman (11:55.700)
And we've now realized Mother Nature
Matt Walker (11:57.300)
didn't make a spectacular blender with sleep.
Lex Fridman (12:00.100)
You've mentioned the idea of conscious states.
Lex Fridman (12:03.180)
Do you think of sleep
Lex Fridman (12:04.940)
as a fundamentally different conscious state than awakeness?
Lex Fridman (12:11.100)
And how many conscious states are there
Lex Fridman (12:13.340)
so when you're into it,
Matt Walker (12:14.660)
you're understanding of what the mind can do,
Lex Fridman (12:17.380)
do you think awake state, sleep state,
Lex Fridman (12:20.500)
or is there some kind of continuum?
Lex Fridman (12:22.700)
There's a complicated state transition diagram.
Lex Fridman (12:26.220)
Like how do you think about this whole space?
Lex Fridman (12:28.580)
I think about it as a state space diagram.
Lex Fridman (12:32.060)
And I think it's probably more of a continuum
Lex Fridman (12:34.100)
than we have believed it to be or suggested it to be.
Lex Fridman (12:37.700)
So we used to think absent of anesthesia
Lex Fridman (12:41.420)
that there were already three main states of consciousness.
Matt Walker (12:44.540)
There was being awake, being in non rapid eye movement sleep
Lex Fridman (12:48.860)
or non dream sleep,
Lex Fridman (12:50.340)
and then being in rapid eye movement sleep or dream sleep.
Lex Fridman (12:53.300)
And those were the three states
Matt Walker (12:55.220)
within which your brain could percolate and be conscious.
Lex Fridman (13:00.340)
Conscious during non REM sleep is maybe a stretch to say,
Lex Fridman (13:05.100)
but I still believe there is plenty of consciousness there.
Lex Fridman (13:08.500)
I don't believe that though anymore.
Lex Fridman (13:11.420)
And the reason is because we can have daydreams
Lex Fridman (13:15.900)
and we are in a very different wakeful state
Matt Walker (13:20.140)
in those daydreams than we are when we are as we are now
Lex Fridman (13:23.420)
together present and extra septively focused
Matt Walker (13:27.180)
rather than intra septively focused.
Lex Fridman (13:30.940)
And then we also know that as you are sort of progressing
Matt Walker (13:35.820)
into those different stages of sleep during non REM sleep,
Lex Fridman (13:38.820)
you can also still dream,
Matt Walker (13:40.340)
depends on your definition of dreaming,
Lex Fridman (13:42.340)
but we seem to have some degree of dreaming
Matt Walker (13:44.860)
in almost all stages of sleep.
Lex Fridman (13:48.540)
We've also then found that when you are sleep deprived,
Matt Walker (13:51.940)
there are even individual brain cells will fall asleep.
Lex Fridman (13:56.220)
Despite the animal being, you know,
Matt Walker (13:59.060)
behaviorally from best we can tell awake,
Lex Fridman (14:02.420)
individual brain cells and clusters of brain cells
Matt Walker (14:05.060)
will go into a sleep like state.
Lex Fridman (14:07.740)
And humans do this too.
Matt Walker (14:09.460)
When we are sleep deprived,
Lex Fridman (14:10.940)
we have what are called microsleeps
Matt Walker (14:13.580)
where the eyelid will partially close
Lex Fridman (14:17.180)
and the brain essentially falls lapses
Matt Walker (14:20.540)
into a state of sleep,
Lex Fridman (14:23.060)
but behaviorally you seem to be awake.
Lex Fridman (14:25.300)
And the danger here is road traffic accidents.
Lex Fridman (14:28.820)
So these are the,
Lex Fridman (14:30.820)
what we call these sort of microsleep events at the wheel.
Lex Fridman (14:34.780)
Now, if you're traveling at 65 miles an hour
Matt Walker (14:38.100)
in a two ton vehicle,
Lex Fridman (14:40.340)
you know, it takes probably around one second
Matt Walker (14:42.740)
to drift from one lane to the next
Lex Fridman (14:44.340)
and it takes two seconds to go completely off the road.
Lex Fridman (14:48.140)
So if you have one of these microsleeps at the wheel,
Lex Fridman (14:50.620)
you know, it could be the last microsleep
Matt Walker (14:52.540)
that you ever have.
Lex Fridman (14:54.580)
But I don't now see it as a set of,
Matt Walker (14:57.460)
you know, very binary distinct,
Lex Fridman (15:00.220)
you know, step function state.
Matt Walker (15:02.260)
It's not a one or a zero.
Lex Fridman (15:04.460)
I see it more of a, as a continuum.
Lex Fridman (15:07.020)
So I've for five, six years at MIT
Lex Fridman (15:13.460)
really focused on this human side of driving question.
Lex Fridman (15:17.740)
And one of the big concerns is the microsleeps,
Lex Fridman (15:23.180)
drowsiness, these kinds of ideas.
Lex Fridman (15:25.340)
And one of the open questions was,
Lex Fridman (15:27.100)
is it possible through computer vision to detect
Lex Fridman (15:29.940)
or any kind of sensors?
Lex Fridman (15:32.340)
The nice thing about computer vision
Matt Walker (15:33.860)
is you don't have to have direct contact to the person.
Lex Fridman (15:36.860)
Is it possible to detect increases in drowsiness?
Matt Walker (15:41.740)
Is it possible to detect these kinds of microsleeps
Lex Fridman (15:44.140)
or actually just sleep in general?
Matt Walker (15:47.260)
Among other things, like distraction,
Lex Fridman (15:49.260)
these are all words that have so many meanings
Lex Fridman (15:52.060)
and so many debates, like attention is a whole nother one.
Lex Fridman (15:55.900)
Just because you're looking at something
Matt Walker (15:57.300)
doesn't mean you're loading in the information.
Lex Fridman (16:00.180)
Just because you're looking away
Matt Walker (16:02.260)
doesn't mean your peripheral vision
Lex Fridman (16:03.780)
can't pick up the important information.
Matt Walker (16:05.780)
There's so many complicated vision science things there.
Lex Fridman (16:08.860)
So I wonder if you could say something to,
Matt Walker (16:13.140)
they say the eyes are the windows to the soul.
Lex Fridman (16:15.260)
Do you think the eyes can reveal
Matt Walker (16:19.140)
something about sleepiness through computer vision,
Lex Fridman (16:25.700)
just looking at the video of the face?
Lex Fridman (16:27.580)
And Andrew Huberman and I, your friend,
Lex Fridman (16:30.180)
have talked about this.
Matt Walker (16:31.020)
I would love to work on this together.
Lex Fridman (16:33.620)
It's a fascinating problem.
Lex Fridman (16:35.620)
But drowsiness is a tricky one.
Lex Fridman (16:37.180)
So there's, what kind of information?
Matt Walker (16:39.340)
There's blinking and there's eye movement.
Lex Fridman (16:42.700)
And those are the ones that can be picked up
Matt Walker (16:46.020)
with computer vision.
Lex Fridman (16:46.860)
Do you think those are signals that could be used
Lex Fridman (16:48.980)
to say something about where we are in this continuum?
Lex Fridman (16:52.660)
Yeah, I do.
Lex Fridman (16:53.540)
And I think there are a number of other features too.
Lex Fridman (16:55.580)
I think, you know, aperture of eye.
Lex Fridman (16:59.460)
So in other words, partial closures, full closures,
Lex Fridman (17:03.100)
duration of those closures, duration of those partial
Matt Walker (17:06.460)
closures of the eyelid.
Lex Fridman (17:09.380)
I think there may be some information in the pupil as well,
Matt Walker (17:13.380)
because as we're transitioning between those states,
Lex Fridman (17:16.420)
there are changes in what's called
Matt Walker (17:17.900)
the automatic nervous system,
Lex Fridman (17:19.300)
or technically it's called the autonomic nervous system,
Matt Walker (17:22.780)
part of which will control your pupillary size.
Lex Fridman (17:27.060)
So I actually think that there is probably
Matt Walker (17:29.820)
a wealth of information.
Lex Fridman (17:32.300)
When you combine that probably with aspects of steering,
Matt Walker (17:37.020)
angle steering maneuver.
Lex Fridman (17:39.860)
And if you can sense the pressure on the pedals as well,
Matt Walker (17:44.460)
my guess is that there is some combinatorial feature
Lex Fridman (17:48.020)
that creates a phenotype of,
Matt Walker (17:52.020)
you are starting to fall asleep.
Lex Fridman (17:54.260)
And as the autonomous controls develop,
Matt Walker (17:57.980)
that it's time for them to kick in.
Lex Fridman (18:00.460)
Some manufacturers, auto manufacturers sort of have
Matt Walker (18:03.460)
something beta version, maybe an alpha version of this
Lex Fridman (18:07.900)
already starting to come online,
Matt Walker (18:09.420)
where they have a little camera in the wheel
Lex Fridman (18:11.900)
that I think tries to look at some features.
Matt Walker (18:14.540)
Almost everybody doing this and it's very alpha.
Lex Fridman (18:19.940)
So, you know, the thing that you currently have,
Matt Walker (18:23.180)
some people have that in their car,
Lex Fridman (18:24.420)
there's a coffee cup or something that comes up
Matt Walker (18:26.460)
that you might be sleepy.
Lex Fridman (18:27.980)
The primary signal that they're comfortable using
Matt Walker (18:31.580)
is the steering wheel reversals.
Lex Fridman (18:33.380)
So basically using your interaction with the steering wheel
Lex Fridman (18:37.460)
and how much you're interacting with it
Lex Fridman (18:39.700)
as a sign of sleepiness.
Lex Fridman (18:40.940)
So if you have to constantly correct the car,
Lex Fridman (18:43.620)
that's a sign of like you starting to drift
Matt Walker (18:46.260)
into microsleep.
Lex Fridman (18:47.380)
I think that's a very, very crude signal.
Matt Walker (18:49.540)
It's probably a powerful one.
Lex Fridman (18:51.180)
There's a whole nother component to this,
Matt Walker (18:52.740)
which is it seems like it's so driver and subject dependent.
Lex Fridman (18:59.220)
How our behavior changes as we get sleepy and drowsy
Matt Walker (19:04.220)
seems to be different in complicated, fascinating ways
Lex Fridman (19:08.140)
where you can't just use one signal.
Matt Walker (19:09.780)
It's kind of like what you're saying,
Lex Fridman (19:11.100)
there has to be a lot of different signals
Matt Walker (19:13.540)
that you should then be able to combine.
Lex Fridman (19:15.380)
The hope is there's the searches for like universal signals
Matt Walker (19:19.780)
that are pretty damn good for like 90% of people.
Lex Fridman (19:23.580)
But I don't think we need
Matt Walker (19:24.620)
to take necessarily quite that approach.
Lex Fridman (19:27.220)
I think what we could do in some clever fashion
Matt Walker (19:31.100)
is using the individual.
Lex Fridman (19:33.500)
So what you and I are perhaps suggesting here
Matt Walker (19:35.620)
is that there is an array of features
Lex Fridman (19:38.420)
that we know provide information
Matt Walker (19:40.860)
that is sensitive to whether or not
Lex Fridman (19:42.780)
you're falling asleep at the wheel.
Matt Walker (19:44.580)
Some of those, let's say that there are 10 of them,
Lex Fridman (19:47.940)
for me, seven of them are the cardinal features.
Matt Walker (19:51.860)
For you, however, you know, six of them
Lex Fridman (19:54.580)
and they're not all the same sort of overlapping
Matt Walker (19:58.100)
are those for you.
Lex Fridman (19:59.980)
I think what we need is algorithms
Matt Walker (1:00:02.420)
The third benefit, however, is that sleep,
Lex Fridman (1:00:05.780)
we've learned more recently is much more intelligent
Matt Walker (1:00:08.660)
than we ever gave it credit for.
Lex Fridman (1:00:10.700)
Sleep doesn't simply just take individual memories
Lex Fridman (1:00:14.380)
and strengthen them.
Lex Fridman (1:00:15.980)
Sleep will then intelligently integrate and cross link
Lex Fridman (1:00:20.260)
and associate that information together.
Lex Fridman (1:00:24.220)
And it's almost like informational alchemy.
Lex Fridman (1:00:27.420)
So that you wake up the next morning
Lex Fridman (1:00:29.220)
with a revised mind wide web of associations.
Lex Fridman (1:00:34.740)
And that's probably the reason that, you know,
Lex Fridman (1:00:36.820)
you've never been told to stay awake on a problem.
Lex Fridman (1:00:40.740)
And in every language that I've inquired about that phrase
Lex Fridman (1:00:44.900)
or something very similar seems to exist,
Matt Walker (1:00:47.940)
which means to me that this creative associative benefit
Lex Fridman (1:00:52.620)
of sleep transcends cultural boundaries.
Matt Walker (1:00:55.140)
It is a common experience across humanity.
Lex Fridman (1:00:58.380)
Now I should note that I think the French translation
Matt Walker (1:01:05.140)
of that is much closer to you.
Lex Fridman (1:01:07.340)
I think you sleep with a problem.
Matt Walker (1:01:08.980)
Whereas the British, you sleep on a problem.
Lex Fridman (1:01:11.340)
The French, you sleep with a problem.
Matt Walker (1:01:12.900)
I think it says so much about the romantic difference
Lex Fridman (1:01:15.060)
between the British and the French, but let's not go there.
Matt Walker (1:01:19.580)
That's brilliant.
Lex Fridman (1:01:20.420)
So such a subtle, but such a fundamental difference.
Matt Walker (1:01:23.380)
Yeah.
Lex Fridman (1:01:24.220)
Oh, goodness me.
Matt Walker (1:01:25.660)
Sleep with the problem.
Lex Fridman (1:01:27.260)
Yes, exactly.
Matt Walker (1:01:28.540)
That's why I love the French.
Lex Fridman (1:01:31.380)
So, and we can sort of double click on any one of these
Lex Fridman (1:01:35.140)
and go into detail, but the fourth,
Lex Fridman (1:01:38.620)
I became really enchanted by about eight years ago
Matt Walker (1:01:44.020)
in our research, which was this idea of forgetting.
Lex Fridman (1:01:48.380)
And I started to think that forgetting may be the price
Matt Walker (1:01:52.900)
that we pay for remembering.
Lex Fridman (1:01:54.580)
And in that sense, there is an enormous benefit
Matt Walker (1:02:03.300)
to letting go.
Lex Fridman (1:02:05.940)
And you may be thinking, that sounds ridiculous.
Matt Walker (1:02:08.380)
I don't want to forget.
Lex Fridman (1:02:09.740)
In fact, my biggest problem is I keep forgetting things,
Lex Fridman (1:02:13.220)
but the brain has a, well, we believe,
Lex Fridman (1:02:17.900)
has a finite storage capacity.
Matt Walker (1:02:20.500)
We can't prove it yet, but my suspicion is
Lex Fridman (1:02:22.500)
that that's probably true.
Matt Walker (1:02:23.460)
It doesn't have an infinite storage capacity.
Lex Fridman (1:02:25.540)
It has constraints.
Matt Walker (1:02:27.780)
If that's the case, we can't simply go through life
Lex Fridman (1:02:31.540)
being constantly informational aggregators
Matt Walker (1:02:37.740)
unless we are programmed to say,
Lex Fridman (1:02:39.860)
we've got a hard drive space of about 85 to 90 years
Lex Fridman (1:02:43.140)
and we're good and we can do that.
Lex Fridman (1:02:44.780)
Maybe that's true.
Matt Walker (1:02:45.940)
I don't think that's true.
Lex Fridman (1:02:46.940)
I think forgetting is an incredibly good and useful thing.
Lex Fridman (1:02:50.620)
So for example, it's not beneficial
Lex Fridman (1:02:54.180)
from an evolutionary perspective for me to remember
Matt Walker (1:02:57.100)
where I parked my car three years ago.
Lex Fridman (1:03:00.780)
So it's important that I can remember today's parking spot,
Lex Fridman (1:03:04.740)
but I don't want to have the junk kind of DNA
Lex Fridman (1:03:08.100)
from a memory perspective of where I parked my car
Matt Walker (1:03:12.940)
two years ago.
Lex Fridman (1:03:15.020)
Now, I actually have in some ways a problem
Matt Walker (1:03:17.220)
with forgetting, and again, I'm not trying
Lex Fridman (1:03:19.460)
to sort of be laudatory, but you know,
Matt Walker (1:03:22.260)
I tend not to forget too many things.
Lex Fridman (1:03:24.900)
And I don't think that that's a good thing.
Lex Fridman (1:03:27.140)
And there's a wonderful neurologist, Luria,
Lex Fridman (1:03:31.500)
who wrote a book called The Mind of the Mnemonicist.
Lex Fridman (1:03:35.380)
And it was a brilliant book,
Lex Fridman (1:03:37.900)
both because it was written exquisitely,
Lex Fridman (1:03:40.660)
but he was studying these sort of memory savants
Lex Fridman (1:03:44.820)
who basically could remember everything that he gave them.
Lex Fridman (1:03:49.420)
And he tried to find a chink in their armor.
Lex Fridman (1:03:53.540)
And the first half of the book is essentially about him
Matt Walker (1:03:56.860)
seeing how far he can push them before they fail.
Lex Fridman (1:04:01.700)
And he never found that place.
Matt Walker (1:04:03.740)
He could never find a place where they stopped remembering.
Lex Fridman (1:04:08.980)
And then in his brilliance,
Matt Walker (1:04:10.740)
he turned the question on its head.
Lex Fridman (1:04:13.060)
He said, not what is the benefit of constantly remembering,
Lex Fridman (1:04:17.660)
but instead, what is the detriment to never forgetting?
Lex Fridman (1:04:22.220)
And when you start to realize his descriptions
Matt Walker (1:04:24.700)
of those individuals, it's probably a life
Lex Fridman (1:04:26.980)
that you would not want.
Lex Fridman (1:04:29.540)
But it's fascinating both from a human perspective,
Lex Fridman (1:04:31.860)
but also AI perspective.
Matt Walker (1:04:33.460)
There's a big challenge in the machine learning community
Lex Fridman (1:04:38.300)
of how to build systems that are able to remember
Matt Walker (1:04:40.620)
for prolonged periods of time, lifelong continuous learning.
Lex Fridman (1:04:44.900)
So where you build up information over time.
Lex Fridman (1:04:48.100)
So memory is one of the biggest open problems
Lex Fridman (1:04:51.140)
in AI and machine learning.
Lex Fridman (1:04:54.580)
But at the same time,
Lex Fridman (1:04:55.820)
the right way to formulate memory is actually forgetting
Matt Walker (1:05:00.140)
because you have to be exceptionally selective
Lex Fridman (1:05:03.460)
at which kind of stuff you remember.
Lex Fridman (1:05:05.540)
And that's where the step of assimilation,
Lex Fridman (1:05:07.420)
integration that you're referring to is really important.
Matt Walker (1:05:09.900)
I mean, we forget most of the things.
Lex Fridman (1:05:12.660)
And the question is exactly the cost of forgetting
Matt Walker (1:05:16.660)
at the very edge of stuff that could be important
Lex Fridman (1:05:20.380)
or could not be, how do we remember or not those things?
Matt Walker (1:05:24.140)
Like for example, doing a podcast,
Lex Fridman (1:05:28.340)
I've become cognizant of one feature of my forgetting
Matt Walker (1:05:32.340)
that's been problematic, which is I forget names
Lex Fridman (1:05:36.780)
and titles of books and so on.
Lex Fridman (1:05:39.340)
So when I read, I remember ideas.
Lex Fridman (1:05:43.540)
I remember quotes, I remember statements
Lex Fridman (1:05:47.020)
and like that's the space in which I'm thinking.
Lex Fridman (1:05:50.340)
But when you communicate to others,
Matt Walker (1:05:53.060)
you have to say this person in this book said that.
Lex Fridman (1:05:56.660)
So it's the same thing with like Andrew Huberman
Matt Walker (1:05:59.300)
is masterful at this.
Lex Fridman (1:06:01.140)
This is important academia,
Matt Walker (1:06:02.500)
remembering the authors of a paper
Lex Fridman (1:06:04.300)
and the title of the paper as part of remembering the idea.
Lex Fridman (1:06:09.060)
And I've been feeling the cost of not being able
Lex Fridman (1:06:12.940)
to naturally remember those things.
Lex Fridman (1:06:15.460)
And so that's something I need to sort of work on,
Lex Fridman (1:06:17.940)
but that's an example.
Lex Fridman (1:06:18.780)
Are you good with faces?
Lex Fridman (1:06:20.060)
Yes, very good at faces.
Lex Fridman (1:06:21.540)
But not good with names.
Lex Fridman (1:06:23.060)
So I am exactly like you.
Lex Fridman (1:06:25.140)
And there is an understanding of that in the brain too.
Lex Fridman (1:06:28.860)
We understand that there is partitioning of those
Matt Walker (1:06:31.580)
in terms of the territory of the brain
Lex Fridman (1:06:33.260)
that takes care of faces and facts and places
Lex Fridman (1:06:36.060)
and that they can be separate.
Lex Fridman (1:06:37.940)
So I will never forget a face,
Lex Fridman (1:06:40.540)
but as I said, I usually forget very little,
Lex Fridman (1:06:44.460)
but for some reason, names are a struggle.
Matt Walker (1:06:47.580)
I think in some ways,
Lex Fridman (1:06:48.420)
because I'm probably just a slightly anxious person.
Lex Fridman (1:06:50.900)
So when you first meet someone,
Lex Fridman (1:06:52.140)
which is usually the time when a name is introduced,
Matt Walker (1:06:55.340)
you were saying you were sort of anxious maybe
Lex Fridman (1:06:57.460)
about sort of sitting down with me,
Lex Fridman (1:06:59.700)
but I find that a little bit activating.
Lex Fridman (1:07:04.340)
And so it's not as though there's anything wrong
Matt Walker (1:07:06.780)
with my memory.
Lex Fridman (1:07:07.620)
It's just the emotional state I'm in
Matt Walker (1:07:09.500)
when I'm first meeting someone.
Lex Fridman (1:07:11.580)
It's a little bit perturbing,
Lex Fridman (1:07:12.780)
but I will never forget the face.
Lex Fridman (1:07:15.300)
I completely relate to that
Matt Walker (1:07:16.580)
because I almost don't hear people's names
Lex Fridman (1:07:19.140)
when they tell me because I'm so anxious.
Matt Walker (1:07:21.420)
Yeah.
Lex Fridman (1:07:22.900)
But I think there's certain quirks of social interaction
Matt Walker (1:07:27.260)
that show that you care about the person,
Lex Fridman (1:07:30.460)
that you remember that person,
Matt Walker (1:07:31.860)
that they matter to you,
Lex Fridman (1:07:33.580)
that they had an impact on you.
Lex Fridman (1:07:35.580)
And one of the ways to show that
Lex Fridman (1:07:36.980)
is you remember their name.
Lex Fridman (1:07:39.020)
But that's a quirk to me
Lex Fridman (1:07:40.060)
because a lot of people I meet have a deep impact on me,
Lex Fridman (1:07:46.140)
but I can't communicate that unless I know their name,
Lex Fridman (1:07:50.700)
unless I know some of the details
Matt Walker (1:07:54.980)
that we humans seem to use to communicate
Lex Fridman (1:07:58.700)
that we remember each other.
Lex Fridman (1:08:00.180)
What I remember well is the feeling we shared,
Lex Fridman (1:08:04.980)
is the experience we shared.
Lex Fridman (1:08:07.420)
What I don't remember well is the detailed labels
Lex Fridman (1:08:10.460)
of those experiences.
Lex Fridman (1:08:12.100)
And I need to certainly work on that.
Lex Fridman (1:08:14.100)
I don't know.
Matt Walker (1:08:15.060)
I think it's just allowing yourself to be innate
Lex Fridman (1:08:19.300)
and who you are is also a beautiful thing too.
Matt Walker (1:08:22.700)
I'm not suggesting it's not important
Lex Fridman (1:08:24.580)
to try and better oneself.
Lex Fridman (1:08:26.900)
But I also sometimes worry about the misery
Lex Fridman (1:08:29.780)
that that puts us in.
Lex Fridman (1:08:31.060)
But like you, I do struggle with name,
Lex Fridman (1:08:35.940)
but I know the first time when we met in the lobby,
Matt Walker (1:08:40.740)
I know exactly what you look like.
Lex Fridman (1:08:43.660)
I know that you were wearing headphones.
Matt Walker (1:08:45.220)
I know the shape and the size of those headphones.
Lex Fridman (1:08:47.580)
You didn't have your black jacket on.
Matt Walker (1:08:49.020)
I know exactly what the weave of your shirt looked like
Lex Fridman (1:08:51.620)
and what your shoes look like.
Lex Fridman (1:08:53.660)
And I knew exactly the height of your,
Lex Fridman (1:08:56.020)
the end of your pants from the top of your shoes.
Lex Fridman (1:08:59.540)
And so those things I don't forget.
Lex Fridman (1:09:02.060)
And I can remember when people,
Matt Walker (1:09:04.740)
I met people two years ago and I'll say,
Lex Fridman (1:09:06.940)
oh yes, we met there.
Lex Fridman (1:09:08.300)
And I remember you had those fantastic boots on.
Lex Fridman (1:09:12.300)
I thought they were pretty great pair of boots.
Lex Fridman (1:09:14.700)
And they're like, how do you,
Lex Fridman (1:09:15.940)
I didn't even remember what I was wearing that day.
Matt Walker (1:09:18.580)
It's fascinating.
Lex Fridman (1:09:19.740)
Yeah, I'm the exact same way,
Lex Fridman (1:09:21.060)
but you can't, until we have Neuralink
Lex Fridman (1:09:23.500)
or something like that,
Matt Walker (1:09:24.340)
we can't communicate that you remember all those things.
Lex Fridman (1:09:26.340)
I know, that's what I wanted.
Lex Fridman (1:09:27.940)
So you have to be able to use tricks
Lex Fridman (1:09:29.820)
of human communication for that.
Lex Fridman (1:09:31.420)
But so that, I mean, that's the,
Lex Fridman (1:09:33.660)
it's ultimately is a trick of like,
Matt Walker (1:09:35.740)
which to remember, which to forget.
Lex Fridman (1:09:37.940)
And the forgetting is so, it's so fascinating to say this.
Matt Walker (1:09:41.060)
I mean, it seems to be deeply connected
Lex Fridman (1:09:44.500)
to that assimilation process.
Lex Fridman (1:09:46.660)
So forgetting, you try to fit all the new stuff
Lex Fridman (1:09:50.620)
into this big web of the old stuff
Lex Fridman (1:09:55.020)
and the things that don't fit, you throw out.
Lex Fridman (1:09:58.220)
I think the assimilation,
Matt Walker (1:10:00.020)
the way I've been thinking about it with sleep
Lex Fridman (1:10:02.060)
and it's particularly sort of dream sleep
Matt Walker (1:10:03.660)
that we think can help with this assimilation
Lex Fridman (1:10:07.300)
is that during wake,
Matt Walker (1:10:09.580)
we have one version of associative processing.
Lex Fridman (1:10:13.540)
And what I mean by that
Matt Walker (1:10:14.380)
is we see the most obvious connections.
Lex Fridman (1:10:17.140)
So I think of wakefulness as a Google search gone right.
Matt Walker (1:10:22.140)
Whereas I see dream sleep as doing something very different.
Lex Fridman (1:10:27.140)
I think dream sleep is a little bit
Matt Walker (1:10:28.500)
like group therapy for memories
Lex Fridman (1:10:31.100)
that everyone gets a name badge
Lex Fridman (1:10:33.500)
and sleep gathers in all of the individual pieces
Lex Fridman (1:10:36.660)
of the day and it sort of starts to get you
Matt Walker (1:10:39.620)
to forces you, in fact, to speak to the people,
Lex Fridman (1:10:42.140)
not at the front of the room
Matt Walker (1:10:43.180)
that you think you've got the most obvious connection with,
Lex Fridman (1:10:45.580)
but to speak with the people all the way
Matt Walker (1:10:47.220)
at the back of the room that at first you think,
Lex Fridman (1:10:48.860)
I've got no idea what's going on in the room.
Matt Walker (1:10:51.140)
You think I've got no obvious connection with them at all.
Lex Fridman (1:10:54.500)
But once you get chatting with them,
Matt Walker (1:10:56.620)
you learn that you do have a very distant,
Lex Fridman (1:10:58.780)
non obvious connection,
Lex Fridman (1:10:59.980)
but it's still a connection on the same.
Lex Fridman (1:11:02.740)
And it's almost as though you're doing a Google search
Matt Walker (1:11:05.300)
where I input Lex Friedman
Lex Fridman (1:11:08.700)
and it doesn't take me to the first page of your home site.
Matt Walker (1:11:12.140)
It takes me to page 20,
Lex Fridman (1:11:13.900)
which is about some like field hockey game in Utah.
Matt Walker (1:11:16.980)
It turns out that there actually is a link.
Lex Fridman (1:11:19.620)
If I look at it, it's a distant, non obvious one.
Lex Fridman (1:11:22.340)
And to me, I find that exciting
Lex Fridman (1:11:24.180)
because when you fuse things together
Matt Walker (1:11:25.860)
that shouldn't normally go together,
Lex Fridman (1:11:27.780)
but when they do, they cause marked advances
Matt Walker (1:11:30.100)
in evolutionary fitness.
Lex Fridman (1:11:31.580)
It sounds like the biological basis of creativity.
Lex Fridman (1:11:34.940)
And that's exactly what I think dream sleep
Lex Fridman (1:11:37.500)
and the algorithm of dream sleep is designed to do.
Matt Walker (1:11:40.620)
It's not a Boolean like system where you have
Lex Fridman (1:11:45.060)
the sort of assumptions of true and false.
Matt Walker (1:11:49.220)
Maybe it's more fuzzy logic system.
Lex Fridman (1:11:52.020)
And I think REM sleep is a perfect environment
Matt Walker (1:11:55.140)
within which we do, it's almost like memory pinball.
Lex Fridman (1:11:58.940)
You get the information that you've learned during the day
Lex Fridman (1:12:02.100)
and then you pull the lever back
Lex Fridman (1:12:03.460)
and you shoot it up into the attic of your brain,
Matt Walker (1:12:07.300)
this cortex filled with all
Lex Fridman (1:12:09.020)
of your past historical knowledge.
Lex Fridman (1:12:11.300)
And you start to bounce it around
Lex Fridman (1:12:12.660)
and see where one of those things lights up
Lex Fridman (1:12:14.540)
and you build a new connection there
Lex Fridman (1:12:15.780)
and you build another one there too.
Matt Walker (1:12:17.500)
You're developing schemas.
Lex Fridman (1:12:19.780)
And so in that way, I think you could argue,
Matt Walker (1:12:23.420)
we dream, therefore we are.
Lex Fridman (1:12:27.060)
Yeah, so in terms of this line between learning
Lex Fridman (1:12:31.140)
and thinking through a new thing
Lex Fridman (1:12:33.780)
that seems to be deeply connected,
Matt Walker (1:12:36.460)
there's this legendary engineer named Jim Keller
Lex Fridman (1:12:40.980)
who keeps yelling at me about this.
Matt Walker (1:12:42.780)
He says it's very effective.
Lex Fridman (1:12:44.740)
He likes to, for difficult problems before bed,
Matt Walker (1:12:49.340)
think about that difficult problem.
Lex Fridman (1:12:51.100)
We're not talking about like drama at work
Matt Walker (1:12:52.900)
or all that kind of stuff.
Lex Fridman (1:12:54.020)
No, like a scientific for him engineering problem.
Matt Walker (1:12:57.900)
He likes to like intensely think about it
Lex Fridman (1:13:01.460)
to prime his mind before sleep and then go to sleep.
Lex Fridman (1:13:05.740)
And then he finds that the next day,
Lex Fridman (1:13:09.740)
he's able to think much clearer
Lex Fridman (1:13:12.020)
and there's new ideas that come,
Lex Fridman (1:13:13.380)
but also just, I guess it's more well integrated.
Lex Fridman (1:13:17.980)
And sometimes during the process of like,
Lex Fridman (1:13:21.500)
he's able to like wake up and like see new insights.
Matt Walker (1:13:26.980)
That's right.
Lex Fridman (1:13:27.820)
If he's deeply sort of aggressively thinking through a problem.
Lex Fridman (1:13:30.820)
And there's many scientific demonstrations of this.
Lex Fridman (1:13:35.300)
The Mendeleev with the periodic table of elements,
Matt Walker (1:13:39.500)
he was trying for months to understand.
Lex Fridman (1:13:42.260)
I mean, talk about an ecumenical problem
Matt Walker (1:13:45.860)
of epic proportions.
Lex Fridman (1:13:47.940)
Here's your question today.
Matt Walker (1:13:49.980)
You have to understand how all of the known elements
Lex Fridman (1:13:52.940)
in the universe fit together in a logical way.
Matt Walker (1:13:55.660)
Good luck, take care.
Lex Fridman (1:13:57.140)
It was non trivial at the time.
Lex Fridman (1:13:58.900)
And he would try and try, he was so obsessed with it.
Lex Fridman (1:14:01.700)
He created playing cards
Matt Walker (1:14:03.980)
with all of the different elements on.
Lex Fridman (1:14:06.620)
And then he would go on these long train journeys
Matt Walker (1:14:09.340)
around Europe and he would just sort of deal these cards
Lex Fridman (1:14:12.740)
in front of them and he would shuffle them,
Matt Walker (1:14:15.180)
shuffling and shuffling.
Lex Fridman (1:14:16.180)
And he would just try to see
Matt Walker (1:14:17.620)
if he could find what the answer was.
Lex Fridman (1:14:20.420)
And then, so the story goes,
Matt Walker (1:14:22.660)
he fell asleep and he had a dream.
Lex Fridman (1:14:25.180)
And in that dream,
Matt Walker (1:14:26.740)
all of these elements started to dance and play around
Lex Fridman (1:14:30.460)
and they snapped into a logical grid,
Matt Walker (1:14:33.140)
atomic weights, et cetera, et cetera.
Lex Fridman (1:14:35.700)
And it wasn't his waking brain
Matt Walker (1:14:39.020)
that solved the problem.
Lex Fridman (1:14:41.340)
It was his sleeping brain
Matt Walker (1:14:42.580)
that solved the impenetrable problem
Lex Fridman (1:14:44.580)
that his waking brain could not.
Lex Fridman (1:14:46.980)
And there's been count,
Lex Fridman (1:14:48.540)
even in the arts and in music,
Matt Walker (1:14:51.140)
some wonderful dreams,
Lex Fridman (1:14:52.780)
Frankenstein, Mary Shelley's epic Gothic novel
Matt Walker (1:14:56.100)
came to her in a dream at Lord Byron's home.
Lex Fridman (1:15:00.460)
And then we've got,
Matt Walker (1:15:03.580)
Paul McCartney.
Lex Fridman (1:15:06.060)
Yesterday, the song came to him in a dream.
Lex Fridman (1:15:08.540)
He was filming, gosh, what was the movie?
Lex Fridman (1:15:12.780)
I don't recall it.
Matt Walker (1:15:13.860)
I should be shocked because I'm from Liverpool myself.
Lex Fridman (1:15:16.260)
And, but he was on Wimpole Street in London and filming.
Lex Fridman (1:15:21.340)
And he came up with that song,
Lex Fridman (1:15:24.580)
the melody in his sleep,
Matt Walker (1:15:26.740)
not to be outdone by the Beatles.
Lex Fridman (1:15:28.660)
And by the way, Let It Be
Matt Walker (1:15:30.540)
also came from a dream that McCartney had.
Lex Fridman (1:15:34.500)
People usually give it religious overtones.
Matt Walker (1:15:38.500)
Mother Mary comes to me speaking words of wisdom,
Lex Fridman (1:15:41.140)
let it be.
Matt Walker (1:15:42.900)
If you've ever asked who Mother Mary is,
Lex Fridman (1:15:45.460)
it's not the biblical content.
Matt Walker (1:15:49.420)
It's his mother.
Lex Fridman (1:15:51.260)
It's Mary McCartney.
Lex Fridman (1:15:54.300)
And she came to him in a dream and gifted him the song.
Lex Fridman (1:15:57.900)
But the best story I've heard
Matt Walker (1:16:00.060)
is not to be outdone by the Beatles.
Lex Fridman (1:16:03.260)
The Stones, Keith Richards,
Matt Walker (1:16:07.500)
who I think once was suggested it.
Lex Fridman (1:16:10.260)
Who was it?
Matt Walker (1:16:11.100)
It was a comedian who was saying that
Lex Fridman (1:16:13.780)
in an interview with Rolling Stone,
Matt Walker (1:16:15.860)
Keith Richards suggested or inferred
Lex Fridman (1:16:17.820)
that young kids should not do drugs.
Lex Fridman (1:16:20.740)
And they said, well, look,
Lex Fridman (1:16:24.700)
young kids can't do drugs
Matt Walker (1:16:26.100)
because you've done all of the drugs.
Lex Fridman (1:16:27.780)
And I always thought that,
Lex Fridman (1:16:29.820)
but Keith Richards described he would always go to bed
Lex Fridman (1:16:34.380)
with his guitar and a tape recorder.
Lex Fridman (1:16:39.780)
And then probably who would have a whole set
Lex Fridman (1:16:42.580)
of other things in the bed with him.
Lex Fridman (1:16:43.900)
And who knows how many other people, but anyway.
Lex Fridman (1:16:47.420)
And then he said in his autobiography,
Lex Fridman (1:16:49.780)
and I'm paraphrasing here,
Lex Fridman (1:16:51.100)
but one morning I woke up and I realized
Matt Walker (1:16:55.180)
that the tape had recorded all the way to the end.
Lex Fridman (1:16:58.620)
So I rewound the tape and I hit play.
Lex Fridman (1:17:02.780)
And there in some kind of ghostly form
Lex Fridman (1:17:05.980)
were the opening chords to Satisfaction,
Matt Walker (1:17:08.860)
the most famous successful Rolling Stone song
Lex Fridman (1:17:11.260)
of all time.
Matt Walker (1:17:13.700)
Followed by then 43 minutes of snoring.
Lex Fridman (1:17:18.060)
That's awesome.
Matt Walker (1:17:19.060)
That riff came to him.
Lex Fridman (1:17:20.460)
One of the most famous riffs in all of rock and roll
Matt Walker (1:17:22.900)
came to him by way of a dream inspired insight.
Lex Fridman (1:17:25.460)
So I think there is too many of those anecdotes.
Lex Fridman (1:17:30.340)
And we've now got the side,
Lex Fridman (1:17:31.420)
I don't rely on anecdotes as science.
Matt Walker (1:17:33.940)
We've now done the studies in the laboratory
Lex Fridman (1:17:35.820)
and we can reliably demonstrate
Matt Walker (1:17:37.580)
that sleep inspires creativity,
Lex Fridman (1:17:39.340)
inspires problem solving capacity.
Matt Walker (1:17:41.820)
Well, the interesting thing is,
Lex Fridman (1:17:43.100)
is it possible to some of the ideas that you talk about
Matt Walker (1:17:45.780)
to turn them into a protocol
Lex Fridman (1:17:47.300)
that could be practiced rigorously?
Lex Fridman (1:17:48.940)
So what Jim Keller espouses is saying,
Lex Fridman (1:17:53.380)
not just the fact that sleep helps you
Matt Walker (1:17:56.860)
increase the creativity,
Lex Fridman (1:17:58.620)
but turn it into a process.
Matt Walker (1:18:00.460)
Like literally, like don't do it accidentally.
Lex Fridman (1:18:06.420)
Like an athlete does certain things
Matt Walker (1:18:08.700)
to optimize their performance.
Lex Fridman (1:18:10.180)
They have a training routine.
Matt Walker (1:18:11.460)
They have a regimen of like cycling and sprints
Lex Fridman (1:18:17.140)
and long distance stuff.
Matt Walker (1:18:18.620)
In the same way, thinking about your job
Lex Fridman (1:18:22.380)
as an idea generator in the engineering space
Matt Walker (1:18:25.300)
is like, this is good for my performance.
Lex Fridman (1:18:27.620)
So like for an hour before bed,
Matt Walker (1:18:29.860)
think through a problem like every night
Lex Fridman (1:18:32.220)
and then use sleep to work through that problem.
Matt Walker (1:18:36.700)
I mean, he's the first person that I heard
Lex Fridman (1:18:39.220)
like of the people I really respect that do like what I do,
Matt Walker (1:18:42.700)
which is like programming engineering type work,
Lex Fridman (1:18:46.260)
like using sleep, not accidentally, but with a purpose,
Matt Walker (1:18:50.780)
like using sleep.
Lex Fridman (1:18:53.020)
That's just basically the difference between,
Matt Walker (1:18:54.900)
as you said, a passive approach to it
Lex Fridman (1:18:57.540)
versus an active deterministic
Matt Walker (1:19:01.900)
or hope for a deterministic approach to it.
Lex Fridman (1:19:04.020)
In other words, that you are actually trying to harness
Matt Walker (1:19:08.460)
the power of sleep in a deliberate way
Lex Fridman (1:19:11.380)
rather than an unthoughtful way.
Matt Walker (1:19:13.980)
I still think that mother nature through it,
Lex Fridman (1:19:17.580)
the 3.6 million years of evolution
Matt Walker (1:19:20.260)
has probably got it mostly figured out
Lex Fridman (1:19:22.580)
in terms of what information should be uploaded at night
Lex Fridman (1:19:25.980)
and worked through.
Lex Fridman (1:19:27.140)
I think her algorithm is probably pretty good at this stage.
Matt Walker (1:19:31.300)
It's not to suggest though,
Lex Fridman (1:19:32.420)
that we can't try to tweak it and nudge it.
Matt Walker (1:19:35.820)
It's a very light hand on the tiller is what he's doing.
Lex Fridman (1:19:39.020)
I don't think there's anything wrong with that.
Matt Walker (1:19:41.900)
Just like, for example, for me,
Lex Fridman (1:19:43.500)
fasting has improved my ability to focus deeply
Lex Fridman (1:19:47.420)
and productivity significantly.
Lex Fridman (1:19:49.740)
And in that same way,
Matt Walker (1:19:52.620)
it's possible that playing with these ideas
Lex Fridman (1:19:55.500)
of thinking before bed or some hours before bed
Matt Walker (1:19:57.940)
or some playing with different protocols
Lex Fridman (1:20:00.300)
will have a significant leap
Matt Walker (1:20:02.020)
over what mother nature naturally does.
Lex Fridman (1:20:04.300)
So if you let your body do what it naturally does,
Matt Walker (1:20:06.700)
you may not achieve the same level of performance
Lex Fridman (1:20:09.380)
because mother nature has not designed us
Matt Walker (1:20:12.980)
to think deeply about chip design
Lex Fridman (1:20:16.460)
or programming artificial intelligence systems.
Matt Walker (1:20:20.540)
Well, she's gifted us the architecture
Lex Fridman (1:20:23.140)
and the capacity to do that.
Lex Fridman (1:20:25.580)
What we do with that is what life's experience dictates.
Lex Fridman (1:20:31.500)
She gives us the blueprint to do many.
Matt Walker (1:20:34.460)
Well, if I were to sort of introspect
Lex Fridman (1:20:37.340)
and self analyze what mother nature wants me to do,
Matt Walker (1:20:39.900)
I think given my current lifestyle
Lex Fridman (1:20:42.780)
that I have food in the fridge
Lex Fridman (1:20:45.220)
and a bed to sleep on,
Lex Fridman (1:20:47.180)
I think what mother nature wants me to do is to be lazy.
Lex Fridman (1:20:51.300)
And so I think I'm actually resisting mother nature
Lex Fridman (1:20:56.620)
because so many of my needs are satisfied.
Lex Fridman (1:20:59.580)
And so I have to resist some of the natural forces
Lex Fridman (1:21:04.220)
of the body and the mind
Matt Walker (1:21:05.780)
when I do some of the things I do.
Lex Fridman (1:21:07.820)
So there's that dance,
Matt Walker (1:21:10.500)
like I've been thinking about doing a startup
Lex Fridman (1:21:12.780)
and that's obviously going against everything
Matt Walker (1:21:15.220)
that my body and mind are telling me to do
Lex Fridman (1:21:18.020)
because it's going to be basically suffering.
Lex Fridman (1:21:21.180)
But the only reason I want...
Lex Fridman (1:21:22.660)
As you know, it will be over.
Matt Walker (1:21:24.660)
Yes, but nevertheless,
Lex Fridman (1:21:29.260)
there's some kind of inner drive that wants me to do it.
Lex Fridman (1:21:31.940)
And then you start to ask a question,
Lex Fridman (1:21:33.700)
well, how do you optimize the things you can't optimize
Matt Walker (1:21:36.460)
like sleep, like diet,
Lex Fridman (1:21:38.060)
like the people that you surround yourself with
Matt Walker (1:21:40.300)
in order to maximize happiness and performance
Lex Fridman (1:21:43.500)
and all those kinds of things without also over optimizing.
Lex Fridman (1:21:47.020)
And that's such an interesting idea from a engineer.
Lex Fridman (1:21:52.780)
So as you may know,
Matt Walker (1:21:55.460)
you don't often get those kinds of ideas from engineers.
Lex Fridman (1:21:59.540)
Engineers usually just don't read books about sleeping.
Matt Walker (1:22:04.020)
They're usually like the...
Lex Fridman (1:22:06.100)
They're not the healthiest of people.
Matt Walker (1:22:11.460)
I think that's changing over time,
Lex Fridman (1:22:13.060)
especially with Silicon Valley,
Matt Walker (1:22:14.060)
especially with the tech sector.
Lex Fridman (1:22:15.460)
People are starting to understand what's a healthy lifestyle,
Lex Fridman (1:22:18.260)
but usually they're kind of on the insane side,
Lex Fridman (1:22:20.980)
especially programmers.
Lex Fridman (1:22:22.660)
But it's nice to hear somebody like that use sleep
Lex Fridman (1:22:27.420)
and use some of the things that you talk about
Matt Walker (1:22:29.380)
strategically on purpose.
Lex Fridman (1:22:33.220)
When I get to that idea of not just trying to use
Lex Fridman (1:22:36.860)
what Mother Nature gave,
Lex Fridman (1:22:38.980)
but seeing if you can do something more or different,
Matt Walker (1:22:45.940)
in a conservative mindset,
Lex Fridman (1:22:49.180)
I would then pose the question at what cost?
Matt Walker (1:22:52.500)
Because when you do something perhaps
Lex Fridman (1:22:55.660)
that deviates from the typical pre programmed,
Matt Walker (1:22:59.060)
you know, Mother Nature's program,
Lex Fridman (1:23:04.100)
I suspect it usually comes at the cost of something else.
Lex Fridman (1:23:07.860)
So maybe he is able to direct and focus
Lex Fridman (1:23:12.420)
his sleeping cognition on those particular topics
Matt Walker (1:23:16.540)
that will gain him better problematic resolution
Lex Fridman (1:23:20.300)
the next day when he wakes up.
Matt Walker (1:23:22.220)
The question is though,
Lex Fridman (1:23:23.300)
at what cost of the other things that didn't make it
Lex Fridman (1:23:26.300)
onto the menu of the finger buffet of sleep that night?
Lex Fridman (1:23:31.980)
And is it that you don't process
Matt Walker (1:23:34.340)
the emotional difficulties or events,
Lex Fridman (1:23:37.540)
and therefore you are less emotionally resolved the next day,
Lex Fridman (1:23:41.140)
but you are more problem resolved the following day.
Lex Fridman (1:23:45.340)
And so I always try to think,
Lex Fridman (1:23:46.940)
and I truly don't want to sound puritanical
Lex Fridman (1:23:51.660)
either about sleep,
Lex Fridman (1:23:52.740)
and I think I've come off that way many a times,
Lex Fridman (1:23:56.220)
especially when I started out in the public.
Matt Walker (1:24:00.100)
The tone of the book, in some ways,
Lex Fridman (1:24:02.300)
I look back and think, could I have been a little softer?
Lex Fridman (1:24:06.300)
And the reason was I was that way back in
Lex Fridman (1:24:10.580)
when I started writing the book,
Matt Walker (1:24:11.660)
which was probably something like 2014 or 15,
Lex Fridman (1:24:16.500)
sleep was the neglected stepsister
Matt Walker (1:24:18.620)
in the health conversation of the day.
Lex Fridman (1:24:21.460)
And I was just so sad to see the amount of suffering
Lex Fridman (1:24:25.300)
and disease and sickness that was caused
Lex Fridman (1:24:27.420)
by insufficient sleep.
Lex Fridman (1:24:29.580)
And for years before I'd been doing public speaking,
Lex Fridman (1:24:33.060)
and I'd tell people about the great things
Matt Walker (1:24:34.980)
that happen when you get sleep.
Lex Fridman (1:24:36.260)
People would say, that's fascinating.
Lex Fridman (1:24:37.900)
And then they would go back and keep doing the same thing
Lex Fridman (1:24:39.980)
about not sleeping enough.
Lex Fridman (1:24:41.740)
And then I realized you can't really speak
Lex Fridman (1:24:43.700)
about the good things that happen.
Matt Walker (1:24:44.820)
It's like the news, what bleeds leads.
Lex Fridman (1:24:46.980)
And if you speak about the alarmingly bad things
Matt Walker (1:24:49.300)
that happen, people tend to have a behavioral change.
Lex Fridman (1:24:52.980)
And so the book as a consequence,
Matt Walker (1:24:55.380)
I think probably came out a little bit on the strong side
Lex Fridman (1:24:59.860)
of trying to convince people.
Matt Walker (1:25:03.620)
Well, you were trying to help a lot of people
Lex Fridman (1:25:05.060)
and that's a powerful way to help a lot of people.
Matt Walker (1:25:07.740)
I was genuinely trying to help people,
Lex Fridman (1:25:09.500)
but certainly for some people for whom sleep
Matt Walker (1:25:12.100)
does not come easy, then it was probably
Lex Fridman (1:25:15.940)
a tricky book to read too.
Lex Fridman (1:25:17.500)
And I think I feel more sensitive to those people now
Lex Fridman (1:25:20.660)
and empathetically connected to them.
Lex Fridman (1:25:23.060)
So I think the, again, the point was simply
Lex Fridman (1:25:27.660)
that I don't mean to sound too puritanical in all of this.
Lex Fridman (1:25:32.580)
And the same way with caffeine and coffee.
Lex Fridman (1:25:36.900)
I am just a scientist and I am not here to tell anyone
Lex Fridman (1:25:40.780)
how to live their life.
Lex Fridman (1:25:41.980)
That is not my job at all.
Lex Fridman (1:25:44.020)
And life is to be lived to a degree
Lex Fridman (1:25:47.180)
and life is to be lived if you want to do a startup.
Matt Walker (1:25:51.500)
All I want to do is empower people
Lex Fridman (1:25:54.060)
with the understanding of the science of sleep.
Lex Fridman (1:25:57.500)
And then you can make an informed choice
Lex Fridman (1:25:59.340)
as to how you want to live your life.
Lex Fridman (1:26:00.980)
And I offer no judgment on how anyone
Lex Fridman (1:26:03.580)
wishes to live their life.
Matt Walker (1:26:05.500)
I just want to try and see if the information
Lex Fridman (1:26:08.580)
that I have about sleep would alternatively change
Lex Fridman (1:26:12.060)
how you would think about your life decisions.
Lex Fridman (1:26:13.740)
And if it doesn't, no problem.
Lex Fridman (1:26:15.460)
And if it does, I hope it's been of use.
Lex Fridman (1:26:18.300)
Well, maybe this is me trying
Matt Walker (1:26:20.620)
to justify my lifestyle to you.
Lex Fridman (1:26:22.900)
But Dr. Seuss said, you know you're in love
Matt Walker (1:26:27.460)
when you can't fall asleep because reality
Lex Fridman (1:26:29.620)
is finally better than your dreams.
Matt Walker (1:26:32.740)
I love that quote too.
Lex Fridman (1:26:34.540)
Okay.
Matt Walker (1:26:37.460)
My sleeping schedule is complicated
Lex Fridman (1:26:41.980)
and it has to do primarily with the fact
Matt Walker (1:26:45.980)
that I love basically everything that I do.
Lex Fridman (1:26:49.580)
And that love takes a form that may not appear
Matt Walker (1:26:53.540)
to be love from the external observer perspective.
Lex Fridman (1:26:56.660)
Cause it's often includes struggle.
Matt Walker (1:26:58.780)
It often includes something that looks like stress
Lex Fridman (1:27:02.180)
even though it's not stress.
Matt Walker (1:27:03.780)
It's like this excitement, it's this turmoil
Lex Fridman (1:27:06.940)
and chaos of passion, of struggling with a problem
Matt Walker (1:27:11.180)
of being sad and down to the point even depressed
Lex Fridman (1:27:15.940)
of how difficult the problem is, the disappointment
Matt Walker (1:27:18.620)
that the last few weeks and months have been a failure
Lex Fridman (1:27:22.060)
and self doubt, all that mix.
Lex Fridman (1:27:25.300)
But I love it.
Lex Fridman (1:27:27.140)
And a part of that is sometimes staying up all night
Matt Walker (1:27:30.340)
working on a thing I'm really passionate about.
Lex Fridman (1:27:33.220)
And that means sleep schedules that are just like,
Matt Walker (1:27:37.500)
you know, sometimes sleeping during the day,
Lex Fridman (1:27:39.860)
sometimes very often sleeping very little
Lex Fridman (1:27:43.220)
but taking naps that are like an hour, two hours and so on.
Lex Fridman (1:27:46.740)
That kind of weird chaos.
Lex Fridman (1:27:48.620)
And now I'll also try to give myself back up.
Lex Fridman (1:27:54.220)
I was trying to like research yesterday
Lex Fridman (1:27:56.180)
is anybody else productive, wild like this?
Lex Fridman (1:27:59.660)
And there's of course a lot of anecdotal evidence
Lex Fridman (1:28:02.140)
and some of it could be just narratives
Lex Fridman (1:28:05.820)
that people have told to the public
Matt Walker (1:28:07.780)
when in reality they sleep way more.
Lex Fridman (1:28:09.860)
But there's a bunch of people that are famous
Matt Walker (1:28:14.940)
for not sleeping much.
Lex Fridman (1:28:16.340)
So on the topic of naps, I read this a long time ago
Lex Fridman (1:28:21.620)
and I checked this, Churchill was big on big naps.
Lex Fridman (1:28:26.300)
And is actually just reading more
Matt Walker (1:28:28.540)
about Winston Churchill's sleep schedule
Lex Fridman (1:28:31.300)
is very much like mine.
Lex Fridman (1:28:33.020)
So I basically wanna give myself the opportunity
Lex Fridman (1:28:36.900)
to at night to stay up all night if I want to.
Lex Fridman (1:28:40.740)
And a good nap is a big part of that in the late evening.
Lex Fridman (1:28:44.780)
Like I'll often, this destroys social life completely
Lex Fridman (1:28:48.060)
but I'll often take a nap in the late afternoon
Lex Fridman (1:28:51.980)
or the evening and that sets me
Matt Walker (1:28:54.020)
if I want to stay up all night.
Lex Fridman (1:28:56.540)
And things like that, that I read that Nikola Tesla
Matt Walker (1:29:00.620)
slept only two hours a night, Edison the same three hours
Lex Fridman (1:29:05.140)
but he actually did the polyphasic sleep
Matt Walker (1:29:07.700)
like where it's just a bunch of naps.
Lex Fridman (1:29:10.260)
What can you say about this madness of love
Lex Fridman (1:29:15.860)
and passion of loving everything you do
Lex Fridman (1:29:18.900)
and the chaos of sleep that might result in?
Matt Walker (1:29:23.380)
I love the Seuss quote and I've had that experience too.
Lex Fridman (1:29:28.740)
Like you, I adore what I do.
Matt Walker (1:29:33.100)
If someone gave you enough money
Lex Fridman (1:29:37.700)
to live the rest of your life,
Matt Walker (1:29:40.260)
got a roof above my head, rice and beans on the table
Lex Fridman (1:29:43.260)
and they said, you don't have to work anymore.
Matt Walker (1:29:45.260)
I would do nothing different.
Lex Fridman (1:29:46.900)
I would do exactly, this sounds a little crass
Lex Fridman (1:29:51.940)
and I hope it doesn't sound this way
Lex Fridman (1:29:53.820)
but being a scientist is not what I do, it's who I am.
Lex Fridman (1:30:03.180)
And when that's the case, sleep, working out,
Lex Fridman (1:30:09.260)
showering and eating are the things that I do
Matt Walker (1:30:12.460)
in between my love affair with sleep.
Lex Fridman (1:30:17.540)
I fell for sleep like a blind roofer.
Lex Fridman (1:30:19.380)
And it was a love affair that started 20 years ago
Lex Fridman (1:30:28.300)
and I remain utterly besotted today.
Matt Walker (1:30:33.100)
It's the most beguiling thing in the world to me.
Lex Fridman (1:30:37.420)
And I could easily and I have, it's kept me up at night.
Matt Walker (1:30:41.540)
When my mind is fizzing with experimental ideas
Lex Fridman (1:30:44.140)
or I think I've got a new hypothesis or theory,
Matt Walker (1:30:47.380)
I will struggle with sleep.
Lex Fridman (1:30:49.140)
I really will, it doesn't come easy to me
Matt Walker (1:30:52.300)
because my mind is just so on fire with those ideas.
Lex Fridman (1:30:56.500)
So I understand the struggle,
Lex Fridman (1:31:01.060)
but I couldn't advocate from a scientific perspective,
Lex Fridman (1:31:07.140)
the schedule because the science just doesn't,
Matt Walker (1:31:11.020)
I would feel as though I'm doing you a disservice
Lex Fridman (1:31:14.780)
to say it's okay, that won't come with some blast radius,
Matt Walker (1:31:20.380)
some health consequences.
Lex Fridman (1:31:22.980)
You can add Margaret Thatcher and Ronald Reagan
Matt Walker (1:31:25.500)
to that list too.
Lex Fridman (1:31:26.660)
Both of them were very proud chest beaters
Matt Walker (1:31:30.860)
of how little sleep that they get.
Lex Fridman (1:31:32.260)
Thatcher said four hours, Reagan something similar.
Lex Fridman (1:31:35.820)
And I, knowing the links that we now know
Lex Fridman (1:31:38.140)
between sleep and Alzheimer's disease,
Matt Walker (1:31:39.860)
I've often wondered whether it was coincidental then
Lex Fridman (1:31:42.900)
that both of them died of the terrible disease of Alzheimer's
Matt Walker (1:31:46.380)
meaning, maybe it doesn't get you by way of
Lex Fridman (1:31:49.740)
being popped out of the gene pool in a car accident
Matt Walker (1:31:52.060)
because you had a microsleep at the wheel at age 32,
Lex Fridman (1:31:55.020)
or it doesn't get you at 42 with heart attack
Matt Walker (1:31:59.700)
or even 52 with cancer or a stroke,
Lex Fridman (1:32:03.780)
maybe it gets you in your seventies.
Matt Walker (1:32:05.660)
I think the elastic band of sleep deprivation
Lex Fridman (1:32:07.740)
can stretch only so far before it snaps
Lex Fridman (1:32:10.740)
and it ultimately seems to snap.
Lex Fridman (1:32:13.620)
Nicola Tesla, I think he died of a coronary thrombosis,
Matt Walker (1:32:21.700)
I believe.
Lex Fridman (1:32:22.700)
And there was a wonderful study done out of Harvard
Matt Walker (1:32:25.380)
where they took a group of people who had no signs
Lex Fridman (1:32:27.860)
of cardiovascular disease.
Lex Fridman (1:32:30.220)
And what they found is that when they track them
Lex Fridman (1:32:32.700)
for years afterwards, they were completely healthy
Matt Walker (1:32:36.380)
to begin with.
Lex Fridman (1:32:37.220)
Those people who are getting less than six hours of sleep
Matt Walker (1:32:40.180)
ended up having a 300% increased risk
Lex Fridman (1:32:43.420)
of developing calcification of the coronary artery,
Matt Walker (1:32:46.500)
which is the major sort of corridor of life for your heart.
Lex Fridman (1:32:51.420)
When someone says, he died of a massive coronary,
Matt Walker (1:32:54.820)
it's because of a blockade of the coronary artery.
Lex Fridman (1:32:58.380)
And Tesla passed away from a coronary thrombosis.
Matt Walker (1:33:03.500)
We also know that insufficient sleep
Lex Fridman (1:33:05.100)
is linked to numerous mental health issues.
Matt Walker (1:33:07.380)
We know that Churchill had a wicked battle with depression.
Lex Fridman (1:33:11.340)
Gosh, my goodness, he used to call it black dog
Matt Walker (1:33:13.260)
that would come and visit him.
Lex Fridman (1:33:15.060)
And I think many of his paintings,
Matt Walker (1:33:16.500)
he was exquisite painter,
Lex Fridman (1:33:18.260)
but some of them would depict his darkness
Matt Walker (1:33:20.780)
with depression as well.
Lex Fridman (1:33:24.940)
Edison is interesting.
Matt Walker (1:33:26.100)
People have argued that he would short sleep
Lex Fridman (1:33:28.580)
and he didn't put much value in sleep.
Matt Walker (1:33:30.260)
Whether or not that's true, we don't know,
Lex Fridman (1:33:31.740)
but he was a habitual napper.
Matt Walker (1:33:33.140)
You're right, during the day,
Lex Fridman (1:33:33.980)
I've got some great pictures of him on his inventor's bench
Matt Walker (1:33:36.340)
taking a nap.
Lex Fridman (1:33:37.300)
And in fact, I believe he set up nap carts around his house
Lex Fridman (1:33:41.060)
so he could nap.
Lex Fridman (1:33:42.580)
But what we also know, a study, again,
Matt Walker (1:33:44.700)
coming out of Harvard just a couple of months ago,
Lex Fridman (1:33:47.820)
demonstrated very clearly that polyphasic sleep
Matt Walker (1:33:50.540)
is associated with worse physical outcomes,
Lex Fridman (1:33:52.980)
worse cognitive outcomes,
Lex Fridman (1:33:54.740)
and especially worse mood outcomes.
Lex Fridman (1:33:57.460)
So from that sense,
Matt Walker (1:33:58.900)
sleeping like a baby is not perfect for adults.
Lex Fridman (1:34:01.660)
So there's a fascinating dance here
Matt Walker (1:34:05.740)
of the mean and the extreme,
Lex Fridman (1:34:09.140)
like the average and the high performers.
Lex Fridman (1:34:13.220)
So I,
Lex Fridman (1:34:17.940)
this gets to like the meaning of life kind of discussion,
Lex Fridman (1:34:21.460)
but let's go that way.
Lex Fridman (1:34:24.820)
And also happiness.
Lex Fridman (1:34:25.940)
So when studying sleep and when studying anything
Lex Fridman (1:34:29.540)
like diet and exercise,
Matt Walker (1:34:31.740)
I think you have to really get a lot more data
Lex Fridman (1:34:35.940)
about individuals to make
Matt Walker (1:34:40.620)
conclusive statement.
Lex Fridman (1:34:41.620)
That's when people talk about like,
Lex Fridman (1:34:43.580)
is meat, red meat good for you or bad for you, right?
Lex Fridman (1:34:47.100)
It's just so often correlated with other life decisions
Matt Walker (1:34:50.700)
when you choose to eat meat or not.
Lex Fridman (1:34:53.100)
My sense is that whatever life decisions you make,
Matt Walker (1:34:58.100)
if they reduce stress and lead to happiness,
Lex Fridman (1:35:02.620)
that's also going to be a big boost
Matt Walker (1:35:04.860)
that needs to be integrated
Lex Fridman (1:35:06.020)
into the plots in the science, right?
Lex Fridman (1:35:07.940)
So I'll give you an example of somebody
Lex Fridman (1:35:10.860)
who is unarguably seen as unhealthy.
Matt Walker (1:35:15.100)
My friend, Mr. David Goggins.
Lex Fridman (1:35:17.340)
So he's clearly, obviously,
Matt Walker (1:35:21.660)
almost on purpose destroying his body.
Lex Fridman (1:35:23.900)
He's destroying his body and to say
Matt Walker (1:35:28.540)
that he's doing the wrong thing or the unhealthy thing
Lex Fridman (1:35:32.660)
feels like, feels wrong.
Lex Fridman (1:35:38.140)
But I'm not sure exactly in which way he feels wrong.
Lex Fridman (1:35:41.620)
One of the things I'm bothered by,
Lex Fridman (1:35:43.740)
and again, I apologize for the therapy sessions,
Lex Fridman (1:35:48.420)
a framework of this,
Lex Fridman (1:35:49.820)
but I'm bothered by the fact that a lot of people
Lex Fridman (1:35:55.820)
tell me or David that they're doing things wrong.
Matt Walker (1:36:02.220)
A lot of people in my life, when they see me not sleep,
Lex Fridman (1:36:06.460)
they'll tell me to sleep more.
Matt Walker (1:36:09.260)
Now they're correct, but one fundamental aspect
Lex Fridman (1:36:13.940)
that I'd like to complain about is not enough people,
Matt Walker (1:36:18.300)
almost nobody, especially people that care for me,
Lex Fridman (1:36:22.420)
will come to me and say,
Matt Walker (1:36:25.820)
you have a dream, work harder.
Lex Fridman (1:36:34.660)
It's like the healthy thing should be a component
Matt Walker (1:36:39.660)
of a life well lived, but not everything.
Lex Fridman (1:36:44.420)
And I don't know what to do with that
Matt Walker (1:36:45.820)
because you certainly don't want to espouse.
Lex Fridman (1:36:48.420)
And just like you said, when you were working in your book,
Matt Walker (1:36:51.380)
there is a belief, sleep was a secondary citizen
Lex Fridman (1:36:55.900)
in the full spectrum of what's a healthy life.
Lex Fridman (1:36:59.060)
But at the same time, I'm bothered by in Silicon Valley
Lex Fridman (1:37:02.340)
and all these kinds of work environments
Matt Walker (1:37:05.580)
that I get to work with, with engineers,
Lex Fridman (1:37:07.460)
is there's to me too much focus on work life balance.
Lex Fridman (1:37:12.060)
And what that usually starts meaning is like,
Lex Fridman (1:37:16.100)
yeah, yeah, of course, it's good to have a social life,
Matt Walker (1:37:18.500)
it's good to have a family,
Lex Fridman (1:37:19.540)
it's good to eat well and sleep well,
Lex Fridman (1:37:23.340)
but we should also discover our passion.
Lex Fridman (1:37:25.460)
We should also give ourselves a chance
Matt Walker (1:37:30.140)
to work our ass off towards a dream
Lex Fridman (1:37:33.860)
and make mistakes and take big risks
Matt Walker (1:37:36.940)
that in the short term seem to sacrifice health.
Lex Fridman (1:37:40.060)
And I think to come back to how you started
Matt Walker (1:37:42.860)
about David Goggins, who I've never met,
Lex Fridman (1:37:45.340)
but who I admire incredibly
Lex Fridman (1:37:48.180)
and have an immense reverence for the man.
Lex Fridman (1:37:51.780)
You said two things,
Lex Fridman (1:37:53.740)
is it wrong to do those things to yourself?
Lex Fridman (1:37:59.900)
And is it unhealthy to do those things to yourself?
Matt Walker (1:38:03.700)
I disagree with the former and I agree with the latter.
Lex Fridman (1:38:07.700)
So from a health biological medicine perspective,
Matt Walker (1:38:12.020)
sleeping in the way that you've described
Lex Fridman (1:38:14.740)
or that other people may be sleeping
Matt Walker (1:38:16.340)
in terms of insufficient amounts,
Lex Fridman (1:38:19.780)
now to your point too about into individual differences,
Matt Walker (1:38:24.340)
usually when I see a bar graph and a mean,
Lex Fridman (1:38:27.140)
I usually say, show me your variance.
Matt Walker (1:38:30.380)
I want to see your variance.
Lex Fridman (1:38:32.140)
In other words, show me the distribution of that effect.
Lex Fridman (1:38:35.420)
How many people were below the mean?
Lex Fridman (1:38:36.940)
How many, is it all tightly clustered around this one thing?
Lex Fridman (1:38:39.980)
So it's a very robust effect
Lex Fridman (1:38:41.620)
or was this huge fan of effect where for some people
Matt Walker (1:38:44.540)
there was no effect at all and other people
Lex Fridman (1:38:46.260)
there was a whopping effect and everything in between.
Lex Fridman (1:38:48.980)
So I don't discount into individual variability,
Lex Fridman (1:38:54.300)
but, and I will come back to those two points about,
Lex Fridman (1:38:57.060)
is it wrong and is it unhealthy in just a second?
Lex Fridman (1:38:59.580)
When it comes to sleep,
Matt Walker (1:39:00.980)
we have found huge amounts of into individual differences
Lex Fridman (1:39:04.660)
in your response to a lack of sleep.
Lex Fridman (1:39:07.220)
But one of the fascinating things,
Lex Fridman (1:39:09.460)
so let's say that I take you
Lex Fridman (1:39:10.900)
and we're going to measure your attention,
Lex Fridman (1:39:13.260)
your emotion, your mood, your blood pressure,
Matt Walker (1:39:16.940)
your blood sugar glucose regulation,
Lex Fridman (1:39:19.180)
your autonomic nervous system
Lex Fridman (1:39:20.620)
and your different gene expression.
Lex Fridman (1:39:22.380)
Let's say I'm just going to measure a whole kaleidoscope
Matt Walker (1:39:25.740)
of different outcomes, brain and body.
Lex Fridman (1:39:28.740)
And I find that on our measure of cognition
Matt Walker (1:39:31.140)
on your attentional ability to focus,
Lex Fridman (1:39:33.580)
you are very resilient.
Matt Walker (1:39:35.180)
You just don't show any impairment at all
Lex Fridman (1:39:37.100)
even after being awake for 36 hours straight.
Matt Walker (1:39:40.860)
Does that mean that you are resilient
Lex Fridman (1:39:42.540)
in all of those other domains as well?
Matt Walker (1:39:44.580)
The answer is no, you're not.
Lex Fridman (1:39:46.380)
So you can be resilient in one,
Lex Fridman (1:39:48.820)
but very vulnerable in another.
Lex Fridman (1:39:51.580)
And we've not found anyone who isn't at least vulnerable
Matt Walker (1:39:56.100)
in one of those domains,
Lex Fridman (1:39:58.340)
meaning that it's somewhat safe to say that
Matt Walker (1:40:02.060)
not getting sufficient sleep will lead
Lex Fridman (1:40:03.980)
to some kind of impairment in any one given individual.
Matt Walker (1:40:07.980)
It may not be the same impairment,
Lex Fridman (1:40:10.540)
but it's likely to be an impairment.
Lex Fridman (1:40:12.620)
But to come back to the question,
Lex Fridman (1:40:14.460)
I think it's wrong to tell anyone
Matt Walker (1:40:16.780)
that it's wrong to do what they're doing,
Lex Fridman (1:40:19.300)
even if they are compromising their sleep,
Matt Walker (1:40:21.700)
even if they're compromising their mental health.
Lex Fridman (1:40:24.780)
As long as they're not hurting anyone else,
Matt Walker (1:40:28.340)
then I think the answer is
Lex Fridman (1:40:31.020)
that's that person's choice.
Matt Walker (1:40:32.940)
Yeah, but that's that person's life.
Lex Fridman (1:40:34.140)
I'd like to push back further.
Lex Fridman (1:40:35.540)
So see, the way you kind of said it,
Lex Fridman (1:40:39.100)
yes, you're absolutely right.
Lex Fridman (1:40:41.660)
But I would like to say a stronger statement,
Lex Fridman (1:40:45.380)
which is you should let go of that judgment
Matt Walker (1:40:49.340)
of somebody is wrong
Lex Fridman (1:40:51.220)
and allow yourself to be inspired
Matt Walker (1:40:53.140)
by the great heights they have reached.
Lex Fridman (1:40:55.860)
So take yourself out of the seat of being a judger
Matt Walker (1:40:59.900)
of what is healthy or not,
Lex Fridman (1:41:01.380)
and appreciate the greatness of a particular human.
Matt Walker (1:41:05.180)
You watch the Olympics,
Lex Fridman (1:41:06.940)
the kind of things that some athletes do
Matt Walker (1:41:09.020)
to reach the very heights.
Lex Fridman (1:41:11.700)
The Olympics are taking years off of their life.
Matt Walker (1:41:14.940)
They suffer depression after the Olympics often.
Lex Fridman (1:41:18.460)
The physiology is disastrous.
Matt Walker (1:41:21.020)
Everything, their personal life,
Lex Fridman (1:41:22.540)
there's their psychology, their physiology,
Matt Walker (1:41:27.140)
everything, it's a giant mess.
Lex Fridman (1:41:28.980)
So the question is about life.
Matt Walker (1:41:32.900)
Healthy now means longevity,
Lex Fridman (1:41:38.980)
quality of life over a prolonged period of time,
Matt Walker (1:41:42.860)
optimum performance over a prolonged period of time.
Lex Fridman (1:41:46.260)
But to me, beauty is reaching great heights.
Lex Fridman (1:41:52.220)
And there's a dance there
Lex Fridman (1:41:54.100)
that sometimes reaching great heights
Matt Walker (1:41:56.220)
requires sacrifice of health
Lex Fridman (1:41:58.300)
and not like a calculation
Matt Walker (1:42:01.420)
where you sat down on a sheet of paper
Lex Fridman (1:42:02.780)
and say, I'm going to take seven years off my life
Matt Walker (1:42:05.700)
for an Olympic gold medal.
Lex Fridman (1:42:07.540)
No, it requires more chaotic journey
Matt Walker (1:42:11.020)
that doesn't do that kind of calculus.
Lex Fridman (1:42:13.300)
And I just want to kind of speak to the,
Matt Walker (1:42:15.820)
in the culture that struggles of what is healthy and not,
Lex Fridman (1:42:19.420)
we want to be able to speak to what is healthy
Lex Fridman (1:42:22.820)
and at the same time be inspired by the great heights
Lex Fridman (1:42:26.460)
that humans reach no matter how healthy
Matt Walker (1:42:29.900)
or unhealthy they live.
Lex Fridman (1:42:32.700)
Yeah, I agree with that.
Matt Walker (1:42:34.140)
I think if that's a flag you're hoisting,
Lex Fridman (1:42:35.500)
I will definitely salute it because it really depends,
Lex Fridman (1:42:38.380)
what are you trying to optimize for in your life?
Lex Fridman (1:42:41.660)
And if you are,
Matt Walker (1:42:43.020)
I think the only danger potentially with that mindset
Lex Fridman (1:42:46.380)
is that if you look at many of the studies
Matt Walker (1:42:50.420)
of old age and end of life,
Lex Fridman (1:42:53.340)
most people say I never look back on my life
Lex Fridman (1:42:57.220)
and wish I worked harder.
Lex Fridman (1:43:01.260)
I wish instead I'd spent more time with family, friends
Lex Fridman (1:43:06.620)
and engaged in that aspect.
Lex Fridman (1:43:08.380)
Now I'm not saying though, coming back to your point,
Matt Walker (1:43:11.300)
that that is the standard rubric for everyone.
Lex Fridman (1:43:13.820)
I don't believe it is too.
Lex Fridman (1:43:15.860)
And there are many things that you and I
Lex Fridman (1:43:17.660)
are both benefiting from today,
Matt Walker (1:43:19.580)
even in the field of medicine,
Lex Fridman (1:43:21.260)
where people have sacrificed their own longevity
Matt Walker (1:43:26.420)
for the quest of solving a particular medical problem.
Lex Fridman (1:43:31.220)
And they died quicker because of their commitment,
Matt Walker (1:43:37.820)
because they wished to try and solve that problem
Lex Fridman (1:43:40.380)
in their pursuit of greatness scientifically.
Lex Fridman (1:43:43.100)
And I now benefit.
Lex Fridman (1:43:44.820)
Am I grateful that they did that?
Matt Walker (1:43:46.580)
Incredibly grateful.
Lex Fridman (1:43:48.460)
You know, a simpler demonstration is this.
Matt Walker (1:43:51.700)
If tonight at 4 a.m. in the morning,
Lex Fridman (1:43:54.540)
I have a ruptured appendix, I have an appendicitis,
Matt Walker (1:43:59.820)
I am incredibly grateful that there is an emergency team
Lex Fridman (1:44:04.580)
that will take me to the hospital at 4 a.m. in the morning.
Matt Walker (1:44:07.700)
They are awake, they're not sleeping and they save my life.
Lex Fridman (1:44:12.380)
And that's part of what their life's mission and quest is.
Lex Fridman (1:44:17.380)
And they saved another's life by, in some ways,
Lex Fridman (1:44:20.620)
shaving a little of their own off.
Lex Fridman (1:44:23.860)
So I don't take, I have no umbrage
Lex Fridman (1:44:27.060)
with that mentality at all.
Matt Walker (1:44:29.340)
I think you just have to be very clear
Lex Fridman (1:44:30.860)
about what you're optimizing for.
Lex Fridman (1:44:34.060)
And my worry is that most people fall into the rat race
Lex Fridman (1:44:39.060)
and they never actually ask the question,
Lex Fridman (1:44:41.380)
why am I doing this?
Lex Fridman (1:44:42.860)
If you're just working nine to five or,
Lex Fridman (1:44:47.860)
and you allow that nine to five to stretch
Lex Fridman (1:44:50.220)
into much longer, but it's nevertheless a job
Matt Walker (1:44:53.340)
that's kind of like wears you down.
Lex Fridman (1:44:55.660)
That's one thing.
Matt Walker (1:44:56.540)
Another thing is when it is like, you're,
Lex Fridman (1:44:59.980)
it's a dream, it's a life mission.
Lex Fridman (1:45:04.460)
And for that, I think as long as you know what it is
Lex Fridman (1:45:09.140)
that you could be doing to yourself
Lex Fridman (1:45:11.100)
and you are comfortable and A okay with that,
Lex Fridman (1:45:15.260)
I have no problem with that at all.
Matt Walker (1:45:17.860)
Again, as I said, as a scientist, I cannot, should not,
Lex Fridman (1:45:21.700)
and will not tell anyone what they should do with their life.
Matt Walker (1:45:24.900)
All I want you to be able to do is say, okay,
Lex Fridman (1:45:28.100)
now I understand more about the,
Matt Walker (1:45:31.700)
previously these would be known unknowns
Lex Fridman (1:45:35.860)
and these were the unknown unknowns.
Lex Fridman (1:45:38.260)
And now I am slightly more cognizant.
Lex Fridman (1:45:41.420)
I have more knowns than I had before
Matt Walker (1:45:46.460)
regarding my sleep and my health,
Lex Fridman (1:45:48.420)
knowing that information,
Lex Fridman (1:45:49.940)
do I still choose to make this decision?
Lex Fridman (1:45:53.860)
And if that's what I offered,
Matt Walker (1:45:57.820)
then I think I've done my job.
Lex Fridman (1:45:59.540)
That's all I want to offer is just added information
Matt Walker (1:46:02.420)
into the decision algorithm.
Lex Fridman (1:46:04.900)
And what you end up choosing as an output of that algorithm
Matt Walker (1:46:09.260)
has nothing to do with me.
Lex Fridman (1:46:11.220)
It's not my business and I will never judge anyone for it.
Lex Fridman (1:46:14.700)
And as I said, I'm immensely grateful for people
Lex Fridman (1:46:16.700)
who have sacrificed much in their lives
Matt Walker (1:46:19.580)
to give me what I have.
Lex Fridman (1:46:21.380)
So you're saying as long as the sacrifice sort of grounded
Matt Walker (1:46:23.940)
in knowledge of what the sacrifice is,
Lex Fridman (1:46:27.540)
that sleep is important, all those kinds of things.
Lex Fridman (1:46:29.020)
And that you're comfortable with it.
Lex Fridman (1:46:30.260)
That is, it is your conscious choice
Matt Walker (1:46:32.140)
rather than feeling as though you're trapped
Lex Fridman (1:46:34.500)
or that you are just, you haven't thought about it.
Lex Fridman (1:46:38.020)
And you start that job at age 32
Lex Fridman (1:46:41.260)
and then you wake up the next morning and you're 65
Lex Fridman (1:46:44.100)
and you think, where did my life go?
Lex Fridman (1:46:45.620)
What was I doing?
Matt Walker (1:46:46.940)
That to me, I would feel, I would want to hug you.
Lex Fridman (1:46:49.500)
And I would say, I'm just, and I'm not saying,
Matt Walker (1:46:52.940)
I don't want to sound belittling here at all.
Lex Fridman (1:46:56.420)
I would just not wish that for you.
Matt Walker (1:46:58.940)
I would wish that you could have thought about
Lex Fridman (1:47:03.940)
what it was that you're doing and not have that regret.
Matt Walker (1:47:06.420)
Yeah, so I guess I'm, this is for you, the listener.
Lex Fridman (1:47:09.860)
I'm coming out of the closet here a little bit.
Matt Walker (1:47:11.820)
The fact that I enjoy the madness I live in.
Lex Fridman (1:47:14.460)
So please do not criticize me, embrace me.
Matt Walker (1:47:17.260)
I understand the sacrifices I'm making.
Lex Fridman (1:47:20.620)
I enjoy sleeping on the floor
Matt Walker (1:47:22.340)
when I'm passionate programming all night
Lex Fridman (1:47:24.820)
and just pass out on the carpet.
Matt Walker (1:47:28.460)
I love this life.
Lex Fridman (1:47:29.940)
Okay, so it's, but it's definitely something I think about
Matt Walker (1:47:33.700)
that there's a balance, a strike where.
Lex Fridman (1:47:37.860)
I just want you to have as much of it though.
Matt Walker (1:47:40.180)
Of life.
Lex Fridman (1:47:44.380)
See, quality of life is important.
Matt Walker (1:47:49.180)
I should have said,
Lex Fridman (1:47:50.180)
I want you to have as much high quality life.
Lex Fridman (1:47:52.860)
And if high quality of life means
Lex Fridman (1:47:57.220)
I spend five decades on this planet,
Lex Fridman (1:48:01.060)
but yet in that time, I am thrilled every day.
Lex Fridman (1:48:04.500)
I'm turned on every day by what I do.
Lex Fridman (1:48:07.740)
And I reveled in this thing called my life's work.
Lex Fridman (1:48:14.060)
I think that that is a 50 year journey
Matt Walker (1:48:17.100)
of absolute delight and fulfillment that you should take.
Lex Fridman (1:48:24.340)
I think about my death all the time.
Matt Walker (1:48:26.540)
I meditate on death.
Lex Fridman (1:48:27.820)
I'm okay to die today.
Lex Fridman (1:48:31.580)
So to me, longevity is not a significant goal.
Lex Fridman (1:48:37.340)
I'm so happy to be alive.
Matt Walker (1:48:40.140)
I don't even think it would suck to die today.
Lex Fridman (1:48:43.460)
I'm as afraid of it today as I will be in 50 years.
Matt Walker (1:48:48.500)
I don't wanna die as much today as I will in 50 years.
Lex Fridman (1:48:51.940)
There's of course all these experiences
Matt Walker (1:48:55.060)
I would like to have, but everything's already amazing.
Lex Fridman (1:48:59.860)
It's like that Lego movie.
Lex Fridman (1:49:01.020)
So I don't know.
Lex Fridman (1:49:02.900)
So to me, I just wanna keep doing this.
Lex Fridman (1:49:06.540)
And there's of course things that could affect,
Lex Fridman (1:49:12.380)
like you mentioned, dementia and these deterioration
Matt Walker (1:49:16.860)
of the mind or the body that can significantly affect
Lex Fridman (1:49:21.140)
the quality of life.
Lex Fridman (1:49:23.540)
And so you want to do.
Lex Fridman (1:49:25.220)
As long as you're aware of that,
Lex Fridman (1:49:26.220)
and that's the price you pay for the entry
Lex Fridman (1:49:29.100)
into this magical kingdom that you are experiencing,
Matt Walker (1:49:32.860)
which is a lovely thing.
Lex Fridman (1:49:34.300)
I feel privileged too.
Matt Walker (1:49:37.020)
I can't believe the life that I live.
Lex Fridman (1:49:38.900)
It's incredible.
Lex Fridman (1:49:41.580)
And just like you, I think about mortality a great deal.
Lex Fridman (1:49:46.700)
I think a lot about death, but I don't worry about death.
Matt Walker (1:49:51.700)
I probably, with the exception of the potential pain
Lex Fridman (1:49:55.660)
that comes before it, that some people,
Matt Walker (1:49:58.020)
many people can suffer, that maybe concerns me.
Lex Fridman (1:50:01.740)
But I actually think about mortality as a tool,
Matt Walker (1:50:06.620)
I use it as a lens through which I can then retrospect.
Lex Fridman (1:50:12.260)
And by placing myself at the point of future mortality,
Matt Walker (1:50:16.540)
I can then use it as a retrospective lens
Lex Fridman (1:50:20.020)
to focus and ask the following question.
Matt Walker (1:50:22.980)
Is there anything I feel I would regret
Lex Fridman (1:50:26.460)
and therefore change in the life that I currently have now?
Matt Walker (1:50:31.220)
That's the way I meditate and use mortality as a question,
Lex Fridman (1:50:35.740)
is to try and course correct and focus my life.
Matt Walker (1:50:39.100)
I worry not about dying,
Lex Fridman (1:50:42.700)
but I like to think about death
Matt Walker (1:50:44.500)
as a way to prioritize my life.
Lex Fridman (1:50:47.180)
If that makes sense, I don't know if that makes sense.
Matt Walker (1:50:49.060)
No, it makes total sense to decide
Lex Fridman (1:50:52.740)
how do you want to live today
Lex Fridman (1:50:55.260)
so that in the future you do not regret
Lex Fridman (1:50:59.020)
the way you've lived today.
Matt Walker (1:51:00.140)
Right, and to place yourself in the future
Lex Fridman (1:51:02.380)
at your point of mortality is one way to, I think,
Matt Walker (1:51:06.260)
as an exercise to retrospectively look back
Lex Fridman (1:51:10.500)
and not lose out on informed choices
Matt Walker (1:51:13.020)
that you could otherwise lose out on
Lex Fridman (1:51:15.420)
if you weren't thinking about mortality.
Matt Walker (1:51:18.060)
Yeah, it clarifies your thinking.
Lex Fridman (1:51:23.220)
So I mentioned I sleep on the floor,
Matt Walker (1:51:24.900)
take naps and power naps, and it's just kind of madness.
Lex Fridman (1:51:28.620)
Is there weirdnesses to your own sleep schedule
Matt Walker (1:51:31.860)
as a scientist that does incredible work,
Lex Fridman (1:51:35.300)
has a lot of things going on,
Matt Walker (1:51:39.340)
has to lead research, has to write research,
Lex Fridman (1:51:41.820)
has to be a science communicator,
Matt Walker (1:51:44.580)
also have a social life, all those kinds of things.
Lex Fridman (1:51:46.780)
Is there certain patterns to your own sleep
Matt Walker (1:51:49.940)
that you regret or you participate in
Lex Fridman (1:51:56.100)
that you find you enjoy?
Matt Walker (1:51:59.540)
Is there some personal stuff,
Lex Fridman (1:52:02.420)
quirks or things you're proud of
Lex Fridman (1:52:04.580)
that you do in terms of your sleep schedule?
Lex Fridman (1:52:07.340)
The funny thing about being a sleep researcher
Matt Walker (1:52:10.580)
is that it doesn't make you immune
Lex Fridman (1:52:13.020)
to the ravages of difficult nights of sleep,
Lex Fridman (1:52:16.300)
and I have battled my own periods of insomnia in my life too.
Lex Fridman (1:52:24.620)
And I think I've been fortunate in ways
Matt Walker (1:52:26.900)
because I know how sleep works
Lex Fridman (1:52:28.460)
and I know how to combat insomnia.
Matt Walker (1:52:30.260)
I know how to get it under control
Lex Fridman (1:52:32.660)
because insomnia in many ways is a condition
Matt Walker (1:52:36.940)
where all of a sudden your sleep controls you
Lex Fridman (1:52:40.500)
rather than you control your sleep.
Matt Walker (1:52:42.540)
Wow, yeah, that's a beautiful way to put it, yeah.
Lex Fridman (1:52:46.780)
And I know when I'm starting to lose control
Lex Fridman (1:52:52.060)
and it's starting to take control,
Lex Fridman (1:52:54.860)
and I understand how to regain,
Lex Fridman (1:52:57.980)
but it doesn't happen overnight.
Lex Fridman (1:53:01.420)
It takes a long time.
Lex Fridman (1:53:03.620)
So you've struggled with insomnia in your life?
Lex Fridman (1:53:06.780)
I have, not all of my life.
Matt Walker (1:53:08.340)
I would say I've probably had three or four
Lex Fridman (1:53:10.340)
really severe bouts, and all of them usually triggered
Matt Walker (1:53:14.860)
by emotional circumstances, by stress.
Lex Fridman (1:53:19.020)
Stress that's connected to actual events in life
Lex Fridman (1:53:22.180)
or stress that's unexplainable?
Lex Fridman (1:53:24.380)
Well, externally triggered.
Matt Walker (1:53:26.580)
Yeah, it's sort of what we would call reactive stress.
Lex Fridman (1:53:33.100)
And so that's sort of point number one
Matt Walker (1:53:36.420)
about the idiosyncrasies.
Lex Fridman (1:53:38.620)
The point number two is that when you are having
Matt Walker (1:53:41.140)
a difficult night of sleep, as a sleep researcher,
Lex Fridman (1:53:44.980)
you basically have become the Woody Allen neurotic
Matt Walker (1:53:47.780)
of the sleep world.
Lex Fridman (1:53:49.820)
Because at that moment, I'm trying to fall asleep
Lex Fridman (1:53:52.980)
and I'm not, and I'm starting to think,
Lex Fridman (1:53:54.980)
okay, my dorsal lateral prefrontal cortex
Matt Walker (1:53:57.020)
is not shutting down.
Lex Fridman (1:53:57.900)
My noradrenaline is not ramping down.
Matt Walker (1:53:59.820)
My sympathetic nervous system
Lex Fridman (1:54:01.140)
is not giving way to my parasympathetic.
Matt Walker (1:54:02.900)
At that point, you are dead in the water
Lex Fridman (1:54:05.380)
for the next two hours and nothing is bringing you back.
Lex Fridman (1:54:08.100)
So there is some irony in that too.
Lex Fridman (1:54:11.420)
I would say for myself though,
Matt Walker (1:54:14.580)
if there is something I'm not proud of,
Lex Fridman (1:54:16.860)
it has been at times railing against my chronotype.
Lex Fridman (1:54:23.100)
So your chronotype is essentially,
Lex Fridman (1:54:25.500)
are you a morning type, evening type
Lex Fridman (1:54:27.300)
or somewhere in between?
Lex Fridman (1:54:29.340)
And there were times because society
Matt Walker (1:54:32.540)
is desperately biased towards the morning types.
Lex Fridman (1:54:37.020)
This notion of the early bird catches the worm.
Matt Walker (1:54:40.500)
Maybe that's true, but I'll also tell you
Lex Fridman (1:54:42.620)
that the second mouse gets the cheese.
Matt Walker (1:54:46.180)
Yeah, so I think one of the issues around,
Lex Fridman (1:54:52.300)
firstly, people don't really understand chronotype
Matt Walker (1:54:55.260)
because I'll have some people
Lex Fridman (1:54:56.540)
when I'm sort of out in the public,
Matt Walker (1:54:58.060)
they'll say, look, I struggle with terrible insomnia.
Lex Fridman (1:55:00.140)
And I'll ask them, is it problems falling asleep
Lex Fridman (1:55:02.300)
or staying asleep?
Lex Fridman (1:55:03.140)
And they'll say, falling asleep.
Lex Fridman (1:55:05.100)
And then I'll say, look, if you are on a desert island
Lex Fridman (1:55:07.860)
with nothing to wake up for, no responsibilities,
Lex Fridman (1:55:11.660)
what time would you normally go to bed
Lex Fridman (1:55:13.140)
and what time would you wake up?
Lex Fridman (1:55:14.260)
And they would say, I'd probably like to go to bed
Lex Fridman (1:55:15.780)
about midnight and wake up maybe eight in the morning.
Lex Fridman (1:55:18.620)
And then I'd say, so what time do you now go to bed?
Lex Fridman (1:55:20.860)
And they'd say, well, I've got to be up for work early.
Lex Fridman (1:55:22.900)
So I get into bed at 10.
Lex Fridman (1:55:25.300)
I say, well, you don't have insomnia.
Matt Walker (1:55:26.740)
You have a mismatch between your biological chronotype
Lex Fridman (1:55:29.820)
and your current sleep schedule.
Lex Fridman (1:55:31.740)
And when you align those two,
Lex Fridman (1:55:33.580)
and I was fighting that for some time too,
Matt Walker (1:55:35.860)
I'm probably mostly right in the middle.
Lex Fridman (1:55:40.740)
I am desperately vanilla, unfortunately,
Matt Walker (1:55:43.660)
in many aspects of life, but this included,
Lex Fridman (1:55:47.020)
I'm neither a strong morning type
Matt Walker (1:55:48.380)
nor a strong evening type.
Lex Fridman (1:55:49.900)
So ideally I'd probably like to go to bed around 11,
Matt Walker (1:55:53.460)
10.30, 11, probably somewhere between 10.30, 11,
Lex Fridman (1:55:56.860)
and wake up, I naturally wake up usually most days
Matt Walker (1:56:00.180)
before my alarm at 7.04, and it's 7.04
Lex Fridman (1:56:05.900)
because why not be idiosyncratic
Lex Fridman (1:56:08.500)
in terms of setting an alarm?
Lex Fridman (1:56:09.340)
I love it.
Lex Fridman (1:56:10.940)
And so I...
Lex Fridman (1:56:13.100)
That's kind of awesome.
Matt Walker (1:56:14.060)
I've never heard about that.
Lex Fridman (1:56:15.020)
That's amazing.
Matt Walker (1:56:16.140)
I'm gonna start doing that now,
Lex Fridman (1:56:17.300)
setting alarms like a little bit off the...
Matt Walker (1:56:20.300)
Yeah, I know.
Lex Fridman (1:56:21.140)
I'm never quite sure why we all...
Matt Walker (1:56:22.380)
It's a celebration of uniqueness.
Lex Fridman (1:56:24.780)
Yeah, and I am quite the odd snowflake in that sense too.
Lex Fridman (1:56:28.780)
So I would usually then try to force myself
Lex Fridman (1:56:31.460)
because I had that same mentality
Matt Walker (1:56:33.820)
that if I wasn't up at 6.30 and in the gym by seven
Lex Fridman (1:56:38.980)
that there was something wrong with me.
Lex Fridman (1:56:41.740)
And I quickly abandoned that.
Lex Fridman (1:56:44.460)
But if I look back, if there was a shameful act
Matt Walker (1:56:46.540)
that I have around my sleep,
Lex Fridman (1:56:47.820)
I think it would be that for some years
Matt Walker (1:56:49.820)
until I really started to get more detailed into sleep.
Lex Fridman (1:56:53.020)
And now I have no shame in telling people
Matt Walker (1:56:56.500)
that I will probably usually wake up around 6.45 naturally,
Lex Fridman (1:57:02.420)
sometimes seven when people are looking at me thinking,
Matt Walker (1:57:06.020)
you're a sloth, you're lazy.
Lex Fridman (1:57:08.740)
And I don't finish my daily workout
Matt Walker (1:57:12.620)
until I'm not working until probably nine o clock
Lex Fridman (1:57:16.900)
in the morning thinking, what are you doing?
Matt Walker (1:57:19.420)
Now I will work late into the day.
Lex Fridman (1:57:22.860)
If I could, I would work 16 hours.
Matt Walker (1:57:25.420)
It's my passion just like yours.
Lex Fridman (1:57:29.380)
So I don't feel shame around that,
Lex Fridman (1:57:31.860)
but I have changed my mentality around that.
Lex Fridman (1:57:35.420)
It's complicated because I'm probably happiest
Matt Walker (1:57:42.100)
going to bed, if I'm being honest, like at 5 a.m.
Lex Fridman (1:57:45.820)
That's fine.
Matt Walker (1:57:46.660)
You're just an extreme evening type.
Lex Fridman (1:57:48.100)
But the problem is it's not that I'm ashamed for it.
Matt Walker (1:57:53.100)
I actually kind of enjoy it because I get to sleep
Lex Fridman (1:57:56.500)
through all the nonsense of like the morning.
Lex Fridman (1:57:59.620)
Isn't that a beautiful thing?
Lex Fridman (1:58:01.140)
Like people are busy with their emails
Lex Fridman (1:58:03.220)
and I just am happy as a cow.
Lex Fridman (1:58:06.300)
And I wake up after all the drama has been resolved.
Lex Fridman (1:58:09.900)
And cows are happy and the drama has been resolved.
Lex Fridman (1:58:12.260)
Exactly.
Lex Fridman (1:58:13.420)
But in society you do, especially,
Lex Fridman (1:58:16.060)
I mean this is what I think about is
Matt Walker (1:58:19.220)
when you work on a larger team,
Lex Fridman (1:58:20.980)
especially with companies, you are,
Matt Walker (1:58:25.060)
everybody's awake at the same time.
Lex Fridman (1:58:26.740)
So that's definitely been a struggle
Matt Walker (1:58:29.620)
to try to figure out, just like you said,
Lex Fridman (1:58:32.860)
how to balance that, how to fit into society
Lex Fridman (1:58:35.460)
and yet be optimal for your chronotype, you said.
Lex Fridman (1:58:38.500)
Yeah, you have to sleep in synchrony with it and harmony.
Matt Walker (1:58:42.900)
Because normally what we know is that if you fight biology,
Lex Fridman (1:58:47.500)
you'll normally lose.
Lex Fridman (1:58:48.860)
And the way you know you've lost is through disease
Lex Fridman (1:58:51.420)
and sickness.
Matt Walker (1:58:52.980)
You said you suffered through several bouts of insomnia.
Lex Fridman (1:58:57.460)
Is there, aside from embracing your chronotype,
Matt Walker (1:59:02.420)
is there advice you can give how to overcome insomnia
Lex Fridman (1:59:05.900)
from your own experience?
Matt Walker (1:59:07.740)
Right now the best method that we have
Lex Fridman (1:59:09.620)
is something called cognitive behavioral therapy
Matt Walker (1:59:11.780)
for insomnia or CBTI for short.
Lex Fridman (1:59:14.980)
And you work with, for people who don't know what it is,
Matt Walker (1:59:18.700)
you work with a therapist for maybe six weeks
Lex Fridman (1:59:21.340)
and you can do it online, by the way,
Matt Walker (1:59:22.700)
I recommend probably jumping online, it's just the easiest.
Lex Fridman (1:59:26.700)
And it will change your beliefs, your habits,
Matt Walker (1:59:31.060)
your behaviors and your general stress
Lex Fridman (1:59:33.020)
around this thing called sleep.
Lex Fridman (1:59:34.740)
And it is just as effective as sleeping pills
Lex Fridman (1:59:36.660)
in the short term.
Lex Fridman (1:59:38.020)
But what's great is that unlike sleeping pills,
Lex Fridman (1:59:40.460)
when you stop working with your therapist,
Matt Walker (1:59:43.060)
those benefits last for years later.
Lex Fridman (1:59:45.740)
Whereas when you stop your sleeping pills,
Matt Walker (1:59:47.260)
you typically have what's called rebound insomnia,
Lex Fridman (1:59:49.460)
where your sleep not only goes back to being
Matt Walker (1:59:51.100)
as bad as it was before, it's usually even worse.
Lex Fridman (1:59:55.300)
For me, I think I found a number of things effective.
Matt Walker (20:01.900)
that can firstly understand when you are well slept.
Lex Fridman (20:04.500)
So let's say that people have sleep trackers at night
Lex Fridman (20:06.980)
and then your car integrates that information
Lex Fridman (20:09.260)
and it understands when you are well slept.
Lex Fridman (20:12.660)
And then you've got the data of the individual behavior
Lex Fridman (20:16.700)
unique to that individual, snowflake like,
Matt Walker (20:20.380)
when they are well slept.
Lex Fridman (20:21.940)
This is the signature of well rested driving.
Matt Walker (20:26.540)
Then you can look at deviations from that
Lex Fridman (20:29.260)
and pattern match it with the sleep history
Matt Walker (20:32.260)
of that individual.
Lex Fridman (20:33.700)
And then I don't need to find the sort of, you know,
Matt Walker (20:37.460)
the one size fits all approach for 99% of the people.
Lex Fridman (20:41.100)
I can create a very bespoke tailor like set of features,
Matt Walker (20:45.460)
a Savile Row suit of sleepiness features.
Lex Fridman (20:49.580)
You know, that would be my,
Matt Walker (20:50.540)
if you want to ask me about moon shots and crazy ideas,
Lex Fridman (20:53.540)
that's where I go.
Lex Fridman (20:54.380)
But to start with, I think your approach is a great one.
Lex Fridman (20:58.180)
Let's find something that covers 99% of the people
Matt Walker (21:02.060)
because the worrying thing about microsleeps of course,
Lex Fridman (21:04.700)
unlike, you know, drugs or alcohol, which you know,
Matt Walker (21:08.300)
certainly is a terrible thing to be behind the wheel.
Lex Fridman (21:11.940)
With those often you react too late.
Lex Fridman (21:17.660)
And that's the reason you get into an accident.
Lex Fridman (21:20.180)
When you fall asleep behind the wheel,
Matt Walker (21:22.820)
you don't react at all.
Lex Fridman (21:25.140)
You know, at that point,
Matt Walker (21:26.220)
there is a two ton missile driving down the street
Lex Fridman (21:28.580)
and no one's in control.
Matt Walker (21:29.940)
That's why those accidents can often be more dangerous.
Lex Fridman (21:34.420)
Yeah, and the fascinating thing is,
Matt Walker (21:37.340)
in the case of semi autonomous vehicles,
Lex Fridman (21:39.420)
like Tesla autopilot,
Matt Walker (21:40.940)
this is where I've had disagreements with Mr. Elon Musk,
Lex Fridman (21:46.980)
and the human factors community,
Matt Walker (21:50.020)
which is this community that one of the big things they study
Lex Fridman (21:53.700)
is human supervision over automation.
Lex Fridman (21:56.780)
So you have like pilots, you know, supervising an airplane
Lex Fridman (22:00.620)
that's mostly flying autonomously.
Matt Walker (22:02.740)
The question is, when we're actually doing the driving,
Lex Fridman (22:07.700)
how do microsleeps or general,
Lex Fridman (22:09.860)
how does drowsiness progress
Lex Fridman (22:12.100)
and how does it affect our driving?
Matt Walker (22:14.020)
That question becomes more fascinating, more complicated
Lex Fridman (22:17.460)
when your task is not driving,
Lex Fridman (22:19.540)
but supervising the driving.
Lex Fridman (22:21.660)
So your task is to take over when stuff goes wrong.
Lex Fridman (22:24.780)
And that is complicated,
Lex Fridman (22:27.140)
but the basic conclusions from many decades
Matt Walker (22:30.260)
is that humans are really crappy at supervising
Lex Fridman (22:34.300)
because they get drowsy and lose vigilance much, much faster.
Matt Walker (22:39.300)
The really surprising thing with Tesla autopilot,
Lex Fridman (22:42.020)
it was surprising to me,
Matt Walker (22:44.260)
surprising to the human factors community,
Lex Fridman (22:46.780)
and in fact, they still argue with me about it,
Matt Walker (22:49.100)
is it seems that humans in Teslas with autopilot
Lex Fridman (22:55.020)
and other similar systems are not becoming less vigilant,
Matt Walker (22:58.540)
at least with the studies we've done.
Lex Fridman (23:01.380)
So there's something about the urgency of driving.
Matt Walker (23:05.100)
I can't, I'm not sure why,
Lex Fridman (23:06.980)
but there's something about the risk,
Matt Walker (23:08.660)
I think the fact that you might die
Lex Fridman (23:11.620)
is still keeping people awake.
Matt Walker (23:14.220)
The question is, as Tesla autopilot
Lex Fridman (23:16.300)
or similar systems get better and better and better,
Lex Fridman (23:19.180)
how does that affect increasing drowsiness?
Lex Fridman (23:21.460)
And that's when you need to have,
Matt Walker (23:23.020)
that's where the big disagreement was,
Lex Fridman (23:25.180)
you need to have driver sensing,
Matt Walker (23:27.100)
meaning driver facing camera
Lex Fridman (23:30.060)
that tracks some kind of information about the face
Matt Walker (23:33.460)
that can tell you drowsiness.
Lex Fridman (23:35.860)
So you can tell the car if you're drowsy
Lex Fridman (23:38.780)
so that the car can be like,
Lex Fridman (23:40.020)
you should be probably driving or pull to the side.
Matt Walker (23:43.700)
Right, or I need to do some of the heavy lifting here.
Lex Fridman (23:47.220)
Yeah, so there needs to be that dance of interaction
Matt Walker (23:50.500)
of a human and machine,
Lex Fridman (23:53.460)
but currently it's mostly steering wheel based.
Lex Fridman (23:56.620)
So this idea that your hands should be
Lex Fridman (23:59.980)
on the steering wheel,
Matt Walker (24:02.180)
that's a sign that you're paying attention
Lex Fridman (24:05.660)
is an outdated and a very crude metric.
Matt Walker (24:09.420)
I agree, yeah.
Lex Fridman (24:11.180)
I think there are far more sophisticated ways
Matt Walker (24:13.300)
that we can solve that problem if we invest.
Lex Fridman (24:17.220)
Can I ask you a big philosophical question
Lex Fridman (24:20.580)
before we get into fun details?
Lex Fridman (24:24.660)
On the topic of conscious states,
Lex Fridman (24:28.340)
how fundamental do you think is consciousness
Lex Fridman (24:31.180)
to the human mind?
Matt Walker (24:33.300)
I ask this from almost like a robotics perspective.
Lex Fridman (24:36.340)
So in your study of sleep,
Lex Fridman (24:38.980)
do you think the hard question of consciousness
Lex Fridman (24:42.020)
that it feels like something to be us,
Matt Walker (24:45.340)
is that like a nice little feature,
Lex Fridman (24:46.820)
like a quirk of our mind,
Lex Fridman (24:50.180)
or is it somehow fundamental?
Lex Fridman (24:51.940)
Because sleep feels like we take a step out
Matt Walker (24:55.780)
of that consciousness a little bit.
Lex Fridman (24:57.780)
So from all your study of sleep,
Lex Fridman (25:00.500)
do you think consciousness is like deeply part of who we are
Lex Fridman (25:04.260)
or is it just a nice trick?
Matt Walker (25:06.900)
I think it's a deeply embedded feature
Lex Fridman (25:09.580)
that I can imagine has a whole panoply
Matt Walker (25:13.300)
of biological benefits.
Lex Fridman (25:16.060)
But to your point about sleep,
Lex Fridman (25:17.660)
what is interesting if you do a lot of dream research
Lex Fridman (25:20.860)
and we've done some,
Matt Walker (25:23.340)
it's very, very rare at all, in fact,
Lex Fridman (25:28.100)
for you to end up becoming someone
Matt Walker (25:31.180)
other than who you are in your dreams.
Lex Fridman (25:33.380)
Now you can have third person perspective dreams
Matt Walker (25:35.900)
where you can see yourself in the dream
Lex Fridman (25:38.740)
as if you're sort of,
Matt Walker (25:40.540)
you've risen above your physical being.
Lex Fridman (25:44.940)
But for the most part,
Matt Walker (25:46.180)
it's very rare that we lose our sense of conscious self.
Lex Fridman (25:51.380)
And maybe I'm sort of doing a sleight of hand
Matt Walker (25:53.660)
because it's really what I'm saying,
Lex Fridman (25:55.020)
it's very rare that we lose our sense
Matt Walker (25:56.580)
of who we are in dreams.
Lex Fridman (25:58.660)
We never do.
Matt Walker (25:59.940)
Now that's not to suggest that dreams aren't utterly bizarre.
Lex Fridman (26:04.380)
And I mean, when you slept last night,
Matt Walker (26:07.780)
which I know may have been perhaps a little less than me,
Lex Fridman (26:12.060)
but when you went into dreaming,
Matt Walker (26:14.740)
you became flagrantly psychotic.
Lex Fridman (26:18.180)
And there are five essentially good reasons.
Matt Walker (26:20.420)
Firstly, you started to see things which were not there,
Lex Fridman (26:23.460)
so you were hallucinating.
Matt Walker (26:25.180)
Second, you believe things that couldn't possibly be true,
Lex Fridman (26:28.260)
so you were delusional.
Matt Walker (26:30.140)
Third, you became confused about time and place and person,
Lex Fridman (26:35.260)
so you're suffering from what we would call disorientation.
Matt Walker (26:38.540)
Fourth, you have wildly fluctuating emotions,
Lex Fridman (26:41.620)
something that psychiatrists
Matt Walker (26:43.620)
will call being affectively labile.
Lex Fridman (26:46.460)
And then how wonderful, you woke up this morning
Lex Fridman (26:48.540)
and you forgot most if not all of that dream experience,
Lex Fridman (26:51.100)
so you're suffering from amnesia.
Matt Walker (26:52.820)
If you were to experience any one of those five things
Lex Fridman (26:55.900)
while you're awake,
Matt Walker (26:56.900)
you would probably be seeking psychological help.
Lex Fridman (27:00.620)
But so I place that as a backdrop
Matt Walker (27:03.940)
against your astute question,
Lex Fridman (27:06.180)
because despite all of that psychosis,
Matt Walker (27:11.060)
there is still a present self nested at the heart of it,
Lex Fridman (27:16.180)
meaning that I think it's very difficult for us
Matt Walker (27:19.780)
to abandon our conscious sense of self.
Lex Fridman (27:24.100)
And if it's that hard,
Matt Walker (27:25.900)
the old adage in some ways,
Lex Fridman (27:27.180)
that you can't outrun your shadow.
Lex Fridman (27:29.260)
But here it's more of a philosophical question,
Lex Fridman (27:31.420)
which is about the conscious mind
Lex Fridman (27:33.660)
and what the state of consciousness actually means
Lex Fridman (27:36.220)
in a human being.
Lex Fridman (27:38.100)
So I think that that to me,
Lex Fridman (27:39.580)
you become so dislocated from so many other rational ways
Matt Walker (27:45.860)
of waking consciousness.
Lex Fridman (27:47.860)
But one thing that won't go away,
Matt Walker (27:49.540)
that won't get perturbed or sort of, you know,
Lex Fridman (27:54.660)
manacled, is this your sense of conscious self?
Matt Walker (27:58.180)
Yeah, that's a strong sign that consciousness
Lex Fridman (28:00.140)
is fundamental to the human mind.
Matt Walker (28:03.380)
Or we're just creatures of habit
Lex Fridman (28:04.900)
who gotten used to having consciousness.
Matt Walker (28:06.860)
Maybe it just takes a lot of either chemical substances
Lex Fridman (28:11.060)
or a lot of like mental work to escape that.
Matt Walker (28:15.980)
I mean, it's like trying to launch a rocket.
Lex Fridman (28:19.340)
You know, the energy that has to be put in
Matt Walker (28:22.060)
to create escape velocity
Lex Fridman (28:24.580)
from the gravitational pull of this thing
Matt Walker (28:26.620)
called planet earth is immense.
Lex Fridman (28:29.060)
Well, the same thing is true
Matt Walker (28:31.140)
for us to abandon our sense of conscious self.
Lex Fridman (28:36.580)
The amount of biological, the amount of substances,
Matt Walker (28:39.380)
the amount of wacky stuff that you have to do
Lex Fridman (28:42.020)
to truly get escape velocity from your conscious self.
Lex Fridman (28:46.420)
What does that tell us about then
Lex Fridman (28:48.380)
the fundamental state of our conscious self?
Matt Walker (28:52.220)
Yeah, it also probably says that it's quite useful
Lex Fridman (28:55.540)
to have consciousness for survival
Lex Fridman (28:58.700)
and for just operation in this world.
Lex Fridman (29:01.420)
And perhaps for intelligence.
Matt Walker (29:02.820)
I'm one of the, on the AI side,
Lex Fridman (29:05.020)
people that think that intelligence requires consciousness.
Lex Fridman (29:10.300)
So like high levels of general intelligence
Lex Fridman (29:12.980)
requires consciousness.
Matt Walker (29:14.460)
Most people in the AI field think like consciousness
Lex Fridman (29:17.700)
and intelligence are fundamentally different.
Matt Walker (29:19.580)
You could build a computer that's super intelligent.
Lex Fridman (29:22.100)
It doesn't have to be conscious.
Matt Walker (29:23.820)
I think that if you define super intelligence
Lex Fridman (29:26.660)
by being good at chess, yes.
Lex Fridman (29:28.580)
But if you define super intelligence
Lex Fridman (29:30.820)
as being able to operate in this living world of humans
Lex Fridman (29:35.020)
and be able to perform all kinds of different tasks,
Lex Fridman (29:37.540)
consciousness, it seems to be somehow fundamental
Matt Walker (29:41.860)
to richly integrate yourself into the human experience,
Lex Fridman (29:46.780)
into society.
Matt Walker (29:48.300)
It feels like you have to be a conscious being.
Lex Fridman (29:50.940)
But then we don't even know what consciousness is
Lex Fridman (29:53.420)
and we certainly don't know how to engineer it
Lex Fridman (29:55.620)
in our machines.
Matt Walker (29:56.660)
I love the fact that there are still questions
Lex Fridman (2:00:00.660)
The first is that I had to really address
Lex Fridman (2:00:02.580)
what was stressful and try to come up with
Lex Fridman (2:00:06.780)
some degree of meaningful rationality around it.
Matt Walker (2:00:11.580)
Because I think one of the things that happens,
Lex Fridman (2:00:13.620)
there's something very, talking about conscious states,
Matt Walker (2:00:15.860)
to come all the way back to, gosh, I don't know,
Lex Fridman (2:00:19.540)
I feel like we've only been chatting for like 20 minutes,
Lex Fridman (2:00:21.740)
but you're gonna tell me it's been a while.
Lex Fridman (2:00:23.340)
Yeah, it's been a while.
Matt Walker (2:00:24.380)
Okay, I'm desperately, I feel terribly sorry.
Lex Fridman (2:00:27.980)
But let's come back to conscious states,
Matt Walker (2:00:29.420)
which is where we started.
Lex Fridman (2:00:32.860)
There is something very strange about the night
Matt Walker (2:00:36.380)
that thoughts and anxieties are not the same
Lex Fridman (2:00:41.340)
as they are in the waking day.
Matt Walker (2:00:43.380)
They are worse, they are bigger.
Lex Fridman (2:00:45.780)
And I at least find that I am far
Matt Walker (2:00:51.900)
more likely to catastrophize and ruminate
Lex Fridman (2:00:56.860)
at night about things that when I wake up the next day
Matt Walker (2:00:59.540)
in the broad light of day,
Lex Fridman (2:01:01.300)
I think it's nowhere near that bad, man.
Lex Fridman (2:01:03.940)
What were you doing?
Lex Fridman (2:01:04.860)
It's not that bad at all.
Lex Fridman (2:01:06.860)
So to gain firstly, some rational understanding
Lex Fridman (2:01:10.380)
of my emotional state that's causing that insomnia
Matt Walker (2:01:14.220)
was very helpful.
Lex Fridman (2:01:15.660)
The second thing was to keep regularity,
Matt Walker (2:01:18.900)
just going to bed at the same time waking up.
Lex Fridman (2:01:21.260)
And here's an unconventional piece of sleep advice.
Matt Walker (2:01:25.340)
After a bad night of sleep, do nothing.
Lex Fridman (2:01:31.820)
Don't wake up any later, don't go to bed any earlier,
Matt Walker (2:01:37.220)
don't nap during the day,
Lex Fridman (2:01:39.620)
and don't drink any more coffee than you would otherwise.
Matt Walker (2:01:42.500)
Because if you end up sleeping later into the morning,
Lex Fridman (2:01:47.140)
you're then not going to be tired
Matt Walker (2:01:49.420)
at your normal time at night.
Lex Fridman (2:01:51.020)
So then you're gonna get into bed thinking,
Matt Walker (2:01:53.180)
well, I had a terrible night of sleep last night.
Lex Fridman (2:01:55.060)
And yes, I slept in this morning to try and compensate,
Lex Fridman (2:01:58.780)
but I'm still gonna get to bed at my normal time.
Lex Fridman (2:02:00.900)
But now you get into bed and you haven't been awake
Matt Walker (2:02:03.580)
for as long as you normally would.
Lex Fridman (2:02:05.380)
So you're not as sleepy as you normally would be.
Lex Fridman (2:02:07.660)
And so now you sit there lying in bed
Lex Fridman (2:02:10.260)
and it's another bad night.
Lex Fridman (2:02:12.100)
And the same thing is, if you go to bed any earlier,
Lex Fridman (2:02:15.900)
so don't wake up any later, wake up at the same time,
Matt Walker (2:02:20.020)
don't go to bed any earlier,
Lex Fridman (2:02:21.540)
because then you're just probably your chronotype,
Matt Walker (2:02:23.740)
your biological rhythm doesn't want you to be asleep.
Lex Fridman (2:02:26.500)
And you think, well, it's a terrible night,
Matt Walker (2:02:28.940)
I'm gonna get into bed at 9 p.m.
Lex Fridman (2:02:31.020)
rather than my standard 10,
Matt Walker (2:02:32.540)
I'm just gonna be lying in bed awake for that hour.
Lex Fridman (2:02:35.220)
Naps will take our double edged sword,
Matt Walker (2:02:37.300)
they can have wonderful benefits.
Lex Fridman (2:02:38.580)
And we've done lots of studies on naps
Matt Walker (2:02:40.420)
for both the brain and the body.
Lex Fridman (2:02:42.060)
But they are a double edged sword in the sense that
Matt Walker (2:02:45.380)
napping will just take the edge off your sleepiness.
Lex Fridman (2:02:49.900)
It's a little bit like a valve on a pressure cooker.
Matt Walker (2:02:52.060)
When you nap during the day,
Lex Fridman (2:02:54.100)
you can take some of that healthy sleepiness
Matt Walker (2:02:56.660)
that you've been building up during the day.
Lex Fridman (2:02:58.940)
And for some people, not all people,
Lex Fridman (2:03:00.700)
but for some people that can then make it harder
Lex Fridman (2:03:02.620)
for them to fall asleep at night
Lex Fridman (2:03:04.060)
and then stay asleep soundly across the night.
Lex Fridman (2:03:07.140)
So the advice would be,
Matt Walker (2:03:08.260)
if you're struggling with sleep at night,
Lex Fridman (2:03:10.060)
don't nap during the day.
Lex Fridman (2:03:12.060)
But if you are not struggling with sleep,
Lex Fridman (2:03:14.540)
and you can nap regularly, naps are just fine.
Lex Fridman (2:03:17.700)
And we can play around with optimal durations
Lex Fridman (2:03:20.180)
depending on what you want.
Matt Walker (2:03:21.580)
Just try not to nap too late into the day
Lex Fridman (2:03:23.740)
because napping late into the day
Matt Walker (2:03:25.220)
is like snacking before your main meal.
Lex Fridman (2:03:27.380)
It just takes the edge off your sleep hunger as it were.
Lex Fridman (2:03:30.380)
But that would be, so that's my unconventional
Lex Fridman (2:03:34.260)
second piece of advice regarding insomnia.
Matt Walker (2:03:37.180)
The third is meditation.
Lex Fridman (2:03:39.020)
I found meditation to be incredibly powerful.
Matt Walker (2:03:41.260)
I started reading about meditation
Lex Fridman (2:03:43.940)
as I was researching that aspect of the book many years ago.
Lex Fridman (2:03:49.220)
And as a hard nose scientist,
Lex Fridman (2:03:51.060)
I thought this sounds very woo woo.
Matt Walker (2:03:53.700)
This is sort of, we all hold hands and sing come by hour
Lex Fridman (2:03:57.340)
and everything's going to be fine with sleep.
Matt Walker (2:03:59.420)
I read the data and it was compelling.
Lex Fridman (2:04:02.660)
I couldn't ignore it.
Lex Fridman (2:04:04.260)
And I started meditating and that was six years ago
Lex Fridman (2:04:08.140)
and I haven't stopped.
Lex Fridman (2:04:09.660)
And I find meditation before bed incredibly powerful.
Lex Fridman (2:04:14.260)
The meditation app companies were perplexed at this at first.
Matt Walker (2:04:17.500)
They want people to meditate during the day.
Lex Fridman (2:04:19.420)
But when they looked at their usage statistics,
Matt Walker (2:04:21.700)
they found that they would have people
Lex Fridman (2:04:23.500)
in the morning meditating.
Lex Fridman (2:04:24.980)
And then there's a huge number of people
Lex Fridman (2:04:26.900)
using the meditation app in the evening.
Lex Fridman (2:04:28.940)
What they were doing was self medicating their insomnia.
Lex Fridman (2:04:32.500)
And they finally, rather than railing against it,
Matt Walker (2:04:34.940)
they started to see it as a cash cow, rightly so.
Lex Fridman (2:04:39.660)
So I found meditation to be helpful.
Matt Walker (2:04:41.820)
Having a wind down routine
Lex Fridman (2:04:43.380)
is the other thing that's critical for me.
Matt Walker (2:04:45.820)
I can't just go from,
Lex Fridman (2:04:47.500)
because when my mind is switched on
Lex Fridman (2:04:49.140)
and I think you may be like this too,
Lex Fridman (2:04:51.540)
if I get into bed, that Rolodex of thoughts
Lex Fridman (2:04:55.700)
and information and excitement and anxiety and worry
Lex Fridman (2:04:59.980)
is just whirling away.
Lex Fridman (2:05:02.620)
And it's not gonna be a good night for me.
Lex Fridman (2:05:05.220)
So I have to find a wind down routine.
Lex Fridman (2:05:07.580)
And that makes sense when you realize what sleep is like.
Lex Fridman (2:05:10.540)
Sleep is not like a light switch.
Matt Walker (2:05:14.060)
Sleep is much more like trying to land a plane.
Lex Fridman (2:05:16.980)
You know, it takes time to descend down
Matt Walker (2:05:19.260)
onto the terra firma that we call sound sleep at night.
Lex Fridman (2:05:23.260)
And we have this for kids.
Matt Walker (2:05:24.780)
You know, I don't have children,
Lex Fridman (2:05:26.660)
but you know, a lot of parents will say,
Matt Walker (2:05:29.460)
you know, we have to have the bedroom,
Lex Fridman (2:05:33.380)
sorry, the bedtime routine.
Matt Walker (2:05:35.060)
You know, you bathe the kid, you put them in bed,
Lex Fridman (2:05:37.540)
you read them a story.
Matt Walker (2:05:38.820)
You have to go through this routine,
Lex Fridman (2:05:40.500)
this wind down routine for them.
Lex Fridman (2:05:42.340)
And then they fall asleep wonderfully.
Lex Fridman (2:05:44.460)
Why do we abandon that?
Matt Walker (2:05:46.700)
As adults, we need that same wind down routine.
Lex Fridman (2:05:51.380)
So that's been the other thing
Matt Walker (2:05:53.180)
that's been very helpful to me.
Lex Fridman (2:05:54.620)
So don't do anything different.
Matt Walker (2:05:57.140)
If you have a bad night of sleep,
Lex Fridman (2:05:58.780)
keep doing the same thing.
Matt Walker (2:06:00.980)
Manage your anxiety, understand it, rationalize it.
Lex Fridman (2:06:05.380)
Then meditation, and then finally having
Matt Walker (2:06:09.100)
some kind of disengagement wind down routine.
Lex Fridman (2:06:11.940)
Those are the four things that have been very helpful to me.
Matt Walker (2:06:15.580)
That's brilliant.
Lex Fridman (2:06:16.420)
So the regularities really do a lot of work against insomnia.
Matt Walker (2:06:20.580)
Is there,
Lex Fridman (2:06:21.420)
is it possible to have a healthy sleep life
Lex Fridman (2:06:28.700)
without the regularities?
Lex Fridman (2:06:30.980)
I say that because I'm all over the place
Lex Fridman (2:06:34.780)
and I've gotten good at being all over the place.
Lex Fridman (2:06:38.060)
So I'll often, like what happens,
Matt Walker (2:06:40.700)
I'll go stretches of time.
Lex Fridman (2:06:42.100)
There'll be sometimes a month where I,
Matt Walker (2:06:44.660)
my days are like, this is embarrassing to admit,
Lex Fridman (2:06:47.540)
but they're like,
Matt Walker (2:06:49.180)
just you and I here, just you and I.
Lex Fridman (2:06:51.740)
It's like 28 hours or 30 hour days.
Matt Walker (2:06:55.100)
Like I'll just go all the way around
Lex Fridman (2:06:58.540)
comfortably and happily, I love it.
Lex Fridman (2:07:00.780)
And then there'll be a nap.
Lex Fridman (2:07:02.380)
I mean, if you like add up the hours
Matt Walker (2:07:05.300)
when I'm just like sleeping as much as I want,
Lex Fridman (2:07:08.980)
it'd probably be like six hour average per 24 hours.
Matt Walker (2:07:12.740)
Like that kind of, so it works out nicely,
Lex Fridman (2:07:16.660)
maybe even seven hours, I don't know.
Lex Fridman (2:07:18.460)
But that it's obviously irregular
Lex Fridman (2:07:21.500)
and there's chaos in the whole thing.
Matt Walker (2:07:23.620)
Like sometimes it's shorter sleep,
Lex Fridman (2:07:25.380)
sometimes it's longer.
Lex Fridman (2:07:26.700)
Is that totally not a good thing, do you think?
Lex Fridman (2:07:31.220)
The best evidence that we have to speak to this question
Matt Walker (2:07:34.060)
is people who are doing rotating shifts.
Lex Fridman (2:07:37.580)
And unfortunately the news is not good.
Matt Walker (2:07:41.940)
They usually have a higher instance of many diseases
Lex Fridman (2:07:45.780)
such as depression, diabetes, cardiovascular disease,
Matt Walker (2:07:50.740)
obesity, stroke.
Lex Fridman (2:07:54.020)
And again, that's just me communicating the data
Matt Walker (2:08:04.060)
that we have and I'm not telling you
Lex Fridman (2:08:06.500)
that you should do anything different.
Matt Walker (2:08:08.780)
The other thing is that there's nothing in your biology
Lex Fridman (2:08:13.220)
that suggests that that's how your body was designed
Matt Walker (2:08:16.460)
to sleep.
Lex Fridman (2:08:18.180)
It is a system that loves habit.
Matt Walker (2:08:22.020)
You know, if your circadian clock in your brain,
Lex Fridman (2:08:27.860)
it's called the suprachiasmatic nucleus,
Matt Walker (2:08:30.820)
sits in the middle of your brain, had a personality trait,
Lex Fridman (2:08:33.820)
it would be a creature of habit.
Matt Walker (2:08:36.460)
It loves habit.
Lex Fridman (2:08:38.340)
That's how your biology is designed to work
Matt Walker (2:08:42.100)
is through very archetypal prototypical expected cycles.
Lex Fridman (2:08:47.940)
And when we do something different to that,
Matt Walker (2:08:52.460)
then you start to see some of the pressure stress fractures
Lex Fridman (2:08:57.340)
in the system.
Lex Fridman (2:08:58.780)
But again, to your point, if that's something
Lex Fridman (2:09:02.540)
that you don't mind, you know, adopting and understanding
Lex Fridman (2:09:06.940)
and then I think you should keep doing
Lex Fridman (2:09:11.820)
what you're doing.
Matt Walker (2:09:12.660)
Yeah, it's complicated.
Lex Fridman (2:09:13.540)
Of course you have to be a student of your own body
Lex Fridman (2:09:15.340)
and explore it.
Lex Fridman (2:09:16.220)
One of the reasons I want to have kids
Matt Walker (2:09:19.860)
is kids enforce a stricter schedule.
Lex Fridman (2:09:23.540)
I think I definitely feel that I'm not living
Matt Walker (2:09:29.700)
the sort of data wise, scientifically speaking,
Lex Fridman (2:09:33.660)
the optimal life.
Lex Fridman (2:09:34.980)
And me just living the way I want to live day to day
Lex Fridman (2:09:37.940)
is perhaps not the optimal way.
Lex Fridman (2:09:40.020)
And there's certain things that I've seen
Lex Fridman (2:09:41.940)
very successful people that I know in my life
Matt Walker (2:09:45.660)
when they get, when they have kids,
Lex Fridman (2:09:48.460)
they actually, the productivity goes up,
Matt Walker (2:09:50.460)
they get their shit together.
Lex Fridman (2:09:51.620)
There's a lot of aspects that, yeah, the regularity.
Matt Walker (2:09:55.460)
I mean, that creatures a habit.
Lex Fridman (2:09:56.820)
That's the thing that's power.
Lex Fridman (2:09:58.860)
And then you start to optimally use the hours
Lex Fridman (2:10:01.500)
that you have in the day.
Matt Walker (2:10:02.700)
Let me ask you about that.
Lex Fridman (2:10:03.540)
Well, actually, I just have one quick point on that too.
Matt Walker (2:10:06.460)
You know, we often think about sleep as a cost,
Lex Fridman (2:10:14.220)
but instead I think of sleep as an investment.
Lex Fridman (2:10:18.460)
And the reason is because your effectiveness
Lex Fridman (2:10:20.660)
and your efficiency when you're well slept
Matt Walker (2:10:24.060)
typically exceeds that when you're not.
Lex Fridman (2:10:27.060)
And to me, it's the idea of if I'm going to boil
Matt Walker (2:10:29.940)
a pot of water, why would I boil it on medium
Lex Fridman (2:10:34.940)
when I could boil it in half the time on high?
Lex Fridman (2:10:39.060)
And I sometimes worry that when I speak
Lex Fridman (2:10:43.140)
to Fortune 500 companies and they're of this mentality
Matt Walker (2:10:46.700)
of longer hours, getting people to rise and grind,
Lex Fridman (2:10:52.380)
the first point is that after about 20 hours of being awake,
Matt Walker (2:10:55.700)
a human being is as cognitively as impaired
Lex Fridman (2:10:58.260)
as they would be if they were legally drunk.
Lex Fridman (2:11:01.260)
And the reason I bring that point up
Lex Fridman (2:11:03.500)
is because I don't know any company or CEO
Matt Walker (2:11:07.940)
who would say, I've got this great team,
Lex Fridman (2:11:10.460)
they're drunk all the time.
Lex Fridman (2:11:12.780)
But we often lord the airport warrior
Lex Fridman (2:11:15.900)
who's flown through three different time zones
Matt Walker (2:11:18.940)
in the past two days, is on email at 2 a.m.
Lex Fridman (2:11:21.540)
and then is in the office at six.
Lex Fridman (2:11:25.420)
And I think there is some aspect, not in all people,
Lex Fridman (2:11:28.580)
but there is sort of some aspect
Matt Walker (2:11:29.980)
of that slight sleep machismo.
Lex Fridman (2:11:32.620)
And that's not what you are very different.
Matt Walker (2:11:36.900)
You are driven by a purity of passion
Lex Fridman (2:11:40.420)
and a very authentic, incredibly genuine goal
Matt Walker (2:11:44.140)
of wanting to do something remarkable with your life.
Lex Fridman (2:11:48.140)
That's not the issue I think I'm speaking about.
Matt Walker (2:11:52.740)
It's just simply that I think
Lex Fridman (2:11:55.060)
maybe this notion of wanting to be awake for longer
Matt Walker (2:12:02.900)
to try and get more done can sometimes be at odds
Lex Fridman (2:12:06.820)
with the fact that you can actually get so much more done
Matt Walker (2:12:11.260)
if you're well slept.
Lex Fridman (2:12:12.660)
And it's this trade off.
Matt Walker (2:12:14.460)
I actually admire people that take the big risk
Lex Fridman (2:12:17.660)
and work hard, whether that means staying up late at night,
Matt Walker (2:12:20.260)
all those kinds of things,
Lex Fridman (2:12:21.900)
but it cannot be in the framework,
Matt Walker (2:12:24.340)
in the context like what Edison said,
Lex Fridman (2:12:26.100)
which is sleep feels like a waste of time.
Lex Fridman (2:12:29.900)
So if you're not sleeping
Lex Fridman (2:12:32.580)
because you think sleep is stupid, that's totally wrong.
Lex Fridman (2:12:36.500)
But if you're not sleeping
Lex Fridman (2:12:37.780)
because you're deeply passionate about something,
Matt Walker (2:12:39.820)
that to me, it's a gray area, of course,
Lex Fridman (2:12:43.380)
but that to me is much more admirable.
Lex Fridman (2:12:45.220)
And everything you're espousing is saying
Lex Fridman (2:12:48.260)
whatever the hell you're doing,
Matt Walker (2:12:49.620)
you better be aware that sleep,
Lex Fridman (2:12:51.660)
long term and short term is really good for you.
Lex Fridman (2:12:54.660)
So if you're not sleeping, you're sacrificing,
Lex Fridman (2:12:57.220)
just make sure you're sacrificing for the right thing.
Matt Walker (2:13:00.060)
I see vodka and getting drunk the same way.
Lex Fridman (2:13:04.020)
I know it's not good for me.
Matt Walker (2:13:05.500)
I know I'm not gonna feel good days after.
Lex Fridman (2:13:08.460)
I know it's gonna decrease my performance.
Lex Fridman (2:13:10.340)
And there's nothing positive about it,
Lex Fridman (2:13:12.780)
except it introduces chaos in my life
Matt Walker (2:13:17.500)
that introduces beautiful experiences
Lex Fridman (2:13:20.300)
that I would not otherwise have.
Matt Walker (2:13:22.100)
It creates this turmoil of social interaction
Lex Fridman (2:13:27.500)
that ultimately makes me happy
Matt Walker (2:13:29.780)
that I've experienced them in the moment
Lex Fridman (2:13:31.900)
and later the stories, you get to meet new people.
Matt Walker (2:13:34.580)
It's like alcohol in this society
Lex Fridman (2:13:36.580)
is an incredible facilitator of that.
Lex Fridman (2:13:40.340)
So that's a good example of not sleeping
Lex Fridman (2:13:43.980)
and drinking way too much vodka.
Matt Walker (2:13:46.380)
Again, it's this notion of life is to be lived to a degree.
Lex Fridman (2:13:51.740)
But if you do have children,
Matt Walker (2:13:55.780)
I think one of the other things
Lex Fridman (2:13:56.820)
that then maybe comes into the picture
Matt Walker (2:13:58.660)
is the fact that now there are other people
Lex Fridman (2:14:03.380)
that you have to live for than yourself.
Matt Walker (2:14:07.620)
Yeah, but come on, like once they're old enough,
Lex Fridman (2:14:10.740)
like if you can't defend for yourself,
Matt Walker (2:14:13.580)
you're too weak, get stronger.
Lex Fridman (2:14:15.620)
It's gonna be that kind of fatherhood.
Matt Walker (2:14:17.780)
I got it, I'm understanding so much more
Lex Fridman (2:14:21.620)
about Lex Freeman than I did before.
Matt Walker (2:14:23.860)
That's why you have to have for me,
Lex Fridman (2:14:27.260)
that would be my wife would be probably softer.
Matt Walker (2:14:29.540)
It's good cop, bad cop, because I think I'm.
Lex Fridman (2:14:33.500)
But of course, actually, because I don't have kids,
Matt Walker (2:14:35.540)
I've seen some tough dudes when they have kids
Lex Fridman (2:14:39.740)
become like the softies.
Matt Walker (2:14:44.340)
They become like, they do everything for their kids.
Lex Fridman (2:14:47.260)
It's become like, it's totally transforms their life.
Matt Walker (2:14:50.660)
I mean, Joe Rogan is an example of that.
Lex Fridman (2:14:53.180)
I just seen so many tough guys completely become changed
Matt Walker (2:14:57.380)
by having kids, which is fascinating to watch
Lex Fridman (2:15:00.420)
because it just shows you how meaningful having kids is
Matt Walker (2:15:03.540)
for a lot of people.
Lex Fridman (2:15:04.380)
Although I would say having chatted with Joe for some time,
Matt Walker (2:15:09.380)
I think he is a delightful,
Lex Fridman (2:15:13.020)
sweetheart, independent of children.
Matt Walker (2:15:14.980)
I think, don't get me wrong,
Lex Fridman (2:15:17.180)
I don't wanna be in a ring with him.
Matt Walker (2:15:19.740)
He would face me five ways till Tuesday,
Lex Fridman (2:15:22.220)
but I think he's a desperately sweet man
Lex Fridman (2:15:24.740)
and a very, very smart individual.
Lex Fridman (2:15:26.700)
Yeah, I mean, but he talks about the compassion he's gained
Matt Walker (2:15:30.300)
from realizing just watching kids grow up
Lex Fridman (2:15:32.940)
that we were all kids at some point,
Matt Walker (2:15:35.060)
you get a new perspective.
Lex Fridman (2:15:37.100)
I think just like me, I still get this with him.
Matt Walker (2:15:40.420)
He's super competitive and there's a certain way
Lex Fridman (2:15:43.380)
to approach life.
Matt Walker (2:15:45.620)
You're striving to do great things
Lex Fridman (2:15:47.700)
and you're competitive against others
Lex Fridman (2:15:49.820)
and that intensity of that aggression,
Lex Fridman (2:15:53.140)
that can lack compassion sometimes and empathy.
Lex Fridman (2:15:56.620)
And when you have children, you get a sense like,
Lex Fridman (2:15:58.980)
oh, everybody was a child at some point,
Matt Walker (2:16:00.940)
everybody was a kid.
Lex Fridman (2:16:02.420)
And you see that whole development process.
Matt Walker (2:16:04.780)
It can definitely enrich,
Lex Fridman (2:16:07.300)
expand your ability to be empathetic.
Matt Walker (2:16:13.420)
Let me ask about diet.
Lex Fridman (2:16:16.180)
So what's the connection between diet and sleep?
Lex Fridman (2:16:19.540)
So I do intermittent fasting,
Lex Fridman (2:16:21.220)
sometimes only one meal a day, sometimes no meals a day.
Matt Walker (2:16:24.740)
Is there a good science on the interaction
Lex Fridman (2:16:26.700)
between fasting and sleep?
Matt Walker (2:16:29.860)
We have some data, I would prefer more,
Lex Fridman (2:16:33.060)
but we have data both on time restricted eating
Lex Fridman (2:16:38.580)
and then we have some data on fasting to a degree.
Lex Fridman (2:16:45.980)
On time restricted eating,
Matt Walker (2:16:49.260)
I think that it has some benefits,
Lex Fridman (2:16:51.300)
although the human replication studies
Matt Walker (2:16:53.020)
have actually not borne out
Lex Fridman (2:16:54.540)
quite the same health benefit extent
Matt Walker (2:16:57.620)
that the animal studies have.
Lex Fridman (2:16:59.060)
There've been some disappointing studies,
Matt Walker (2:17:01.820)
one here close to where we are right now at UCSF recently.
Lex Fridman (2:17:06.820)
So I think time restricted eating can be a good thing
Lex Fridman (2:17:09.940)
and there are many benefits of time restricted eating.
Lex Fridman (2:17:13.140)
Is sleep one of them?
Matt Walker (2:17:14.260)
No, it doesn't seem to be
Lex Fridman (2:17:15.940)
because there are probably at the time
Matt Walker (2:17:17.820)
that we're recording this,
Lex Fridman (2:17:18.740)
three pretty decent studies that I'm aware of.
Matt Walker (2:17:22.420)
Two out of the three were in obese individuals,
Lex Fridman (2:17:25.740)
one out of the three were in healthy weight individuals.
Lex Fridman (2:17:29.340)
And what they found is that time restricted eating
Lex Fridman (2:17:31.580)
in all three of those studies
Matt Walker (2:17:33.500)
didn't have any advantageous benefit to sleep.
Lex Fridman (2:17:36.380)
It didn't necessarily harm sleep,
Lex Fridman (2:17:38.700)
but it didn't seem to improve it.
Lex Fridman (2:17:41.820)
When it comes to fasting though,
Matt Walker (2:17:43.220)
which is a different state,
Lex Fridman (2:17:45.980)
we don't have too many studies,
Matt Walker (2:17:47.500)
experimental studies with longterm fasting.
Lex Fridman (2:17:49.500)
The best data that we have
Matt Walker (2:17:50.780)
is probably from religious practices
Lex Fridman (2:17:53.020)
and probably the most data we have is during Ramadan
Matt Walker (2:17:56.980)
where people will fast for 29 to 30 days
Lex Fridman (2:18:01.100)
from sunrise to sunset.
Lex Fridman (2:18:04.660)
And under those conditions,
Lex Fridman (2:18:07.220)
there are probably five distinct changes that we've seen.
Matt Walker (2:18:13.820)
None of them seem to be particularly good for sleep.
Lex Fridman (2:18:16.220)
The first is that the amount of melatonin
Matt Walker (2:18:18.420)
that you release, and melatonin is a hormone.
Lex Fridman (2:18:20.740)
It's often called the hormone of darkness
Matt Walker (2:18:23.420)
or the vampire hormone,
Lex Fridman (2:18:25.300)
not because it makes you look longingly
Matt Walker (2:18:27.100)
at people's necklines,
Lex Fridman (2:18:28.300)
but it's just because it comes out at night.
Matt Walker (2:18:31.060)
Melatonin signals to your brain and your body
Lex Fridman (2:18:33.660)
that it's dark, it's nighttime, and it's time to sleep.
Matt Walker (2:18:36.980)
Those individuals,
Lex Fridman (2:18:38.220)
when they were undergoing that regimen of fasting,
Matt Walker (2:18:42.580)
the amount of melatonin that was released
Lex Fridman (2:18:44.540)
and when it was released,
Matt Walker (2:18:45.860)
the amount of melatonin decreased
Lex Fridman (2:18:48.060)
and when it was released came later.
Matt Walker (2:18:50.900)
That was the first thing.
Lex Fridman (2:18:52.100)
The second thing was that they ended up finding it harder
Matt Walker (2:18:56.340)
to fall asleep as quickly as they normally would otherwise.
Lex Fridman (2:19:00.420)
The third thing was that the total amount of sleep
Matt Walker (2:19:02.580)
that they were getting decreased.
Lex Fridman (2:19:05.060)
The fourth fascinating thing
Matt Walker (2:19:06.660)
was that a wake promoting chemical
Lex Fridman (2:19:09.140)
called orexin increased.
Lex Fridman (2:19:12.060)
And this is why a lot of people will say,
Lex Fridman (2:19:13.900)
when I'm fasting, it feels like I can stay awake for longer
Lex Fridman (2:19:18.260)
and I'm more alert, I'm more active.
Lex Fridman (2:19:21.500)
And I'll come back from an evolutionary perspective
Lex Fridman (2:19:23.820)
why we understand that to be the case.
Lex Fridman (2:19:26.460)
And then the fourth factor is that fasting
Matt Walker (2:19:28.820)
didn't decrease the amount of deep sleep
Lex Fridman (2:19:31.380)
that seemed to be unaffected.
Matt Walker (2:19:33.140)
It did, however, decrease the amount
Lex Fridman (2:19:35.220)
of REM sleep or dream sleep.
Lex Fridman (2:19:37.260)
And we know that REM sleep dreaming
Lex Fridman (2:19:38.580)
is essential for emotional first aid, mental health,
Matt Walker (2:19:42.300)
it's critical for memory, creativity.
Lex Fridman (2:19:45.140)
It's also critical for several hormone functions.
Matt Walker (2:19:47.260)
It's when there's direct correlations
Lex Fridman (2:19:50.700)
between testosterone release peaks
Matt Walker (2:19:54.180)
just before you go into REM sleep and during REM sleep too.
Lex Fridman (2:19:57.940)
So REM sleep is critical.
Lex Fridman (2:20:00.100)
But so those are the five changes that we've seen.
Lex Fridman (2:20:02.700)
None of them seem to be that advantageous for sleep.
Lex Fridman (2:20:05.980)
But the fourth point that I mentioned,
Lex Fridman (2:20:07.740)
which was orexin, which is this wake promoting chemical
Lex Fridman (2:20:12.180)
and a good demonstration or a very sad demonstration
Lex Fridman (2:20:15.140)
of its power is when it becomes very deficient in the brain
Lex Fridman (2:20:18.780)
and it leads to a condition called narcolepsy
Lex Fridman (2:20:21.660)
where you're just unpredictable with your sleep.
Lex Fridman (2:20:26.660)
So orexin when it's in high concentrations
Lex Fridman (2:20:33.100)
keeps you awake when you lose it.
Matt Walker (2:20:35.140)
It can put you very much into a state of narcolepsy
Lex Fridman (2:20:38.860)
where you're sleeping a lot of the time
Matt Walker (2:20:40.980)
in unpredictable sleep.
Lex Fridman (2:20:43.460)
Why on earth when you are fasting
Lex Fridman (2:20:46.580)
would the brain release awake promoting chemical?
Lex Fridman (2:20:51.660)
And our answer is right now is the following.
Matt Walker (2:20:54.980)
One of the few times that I mentioned before
Lex Fridman (2:20:56.900)
that we see animals undergoing insufficient sleep
Matt Walker (2:21:00.580)
or prolonged sleep deprivation
Lex Fridman (2:21:03.660)
is under conditions of starvation.
Lex Fridman (2:21:06.540)
And that is an extreme evolutionary pressure.
Lex Fridman (2:21:11.020)
And at that point, the brain will forgo some.
Matt Walker (2:21:14.020)
It won't forgo all, but it will forgo some of its sleep.
Lex Fridman (2:21:18.460)
And the reason is so that it can stay awake for longer
Matt Walker (2:21:21.220)
because the sign of starvation is saying to the brain,
Lex Fridman (2:21:24.460)
you can't find food in your normal foraging perimeter,
Matt Walker (2:21:27.900)
you need to stay awake for longer
Lex Fridman (2:21:29.500)
so you can travel outside of your perimeter
Matt Walker (2:21:31.700)
for a further distance
Lex Fridman (2:21:33.980)
and maybe you will find food and save the organism.
Lex Fridman (2:21:37.300)
So in other words, when we fast,
Lex Fridman (2:21:39.660)
it's giving our brain this evolutionary signal
Matt Walker (2:21:43.620)
that you are under conditions of starvation.
Lex Fridman (2:21:46.380)
So the brain responds by saying, oh my goodness,
Matt Walker (2:21:49.020)
I need to release the chemical
Lex Fridman (2:21:50.300)
that helps the organism stay awake for longer
Matt Walker (2:21:52.900)
which is orexin.
Lex Fridman (2:21:54.300)
So that they can forage for more food.
Matt Walker (2:21:57.420)
Now, of course, your brain from an evolutionary perspective
Lex Fridman (2:21:59.940)
doesn't know about this thing called Safeway
Matt Walker (2:22:02.340)
that you could easily go to and break the fast.
Lex Fridman (2:22:05.820)
But that's how we understand fasting.
Lex Fridman (2:22:08.340)
And I think my dear friend, Peter Attia
Lex Fridman (2:22:11.180)
has done a lot of work in this area too.
Matt Walker (2:22:14.060)
I think fasting and David Sinclair's brilliant work,
Lex Fridman (2:22:17.340)
goodness me, what an individual too.
Matt Walker (2:22:20.140)
The work is pretty clear there
Lex Fridman (2:22:21.940)
that time restricted eating and fasting
Matt Walker (2:22:25.100)
have wonderful health benefits.
Lex Fridman (2:22:27.860)
Fasting creates this thing called hormesis,
Matt Walker (2:22:32.740)
just like exercise and low level stress
Lex Fridman (2:22:36.380)
and sauna, heat, shock.
Lex Fridman (2:22:39.780)
And hormesis is a biological process
Lex Fridman (2:22:41.620)
I think as David Sinclair has once said,
Matt Walker (2:22:43.740)
in simple layman's terms is,
Lex Fridman (2:22:45.540)
what doesn't kill you makes you stronger.
Lex Fridman (2:22:47.540)
And I think there is certainly good data
Lex Fridman (2:22:53.300)
that fasting and time restricted eating has many benefits.
Lex Fridman (2:22:56.220)
Is sleep one of them?
Lex Fridman (2:22:57.740)
It doesn't seem to be, it doesn't seem to enhance sleep.
Lex Fridman (2:23:00.660)
But it's interesting to understand its effects on sleep.
Lex Fridman (2:23:04.700)
I've fasted, it's a study of NF2.
Matt Walker (2:23:12.340)
I once fasted 72 hours and another time 48 hours.
Lex Fridman (2:23:16.820)
And I found that I got much less sleep
Lex Fridman (2:23:20.340)
and it was very restful though.
Lex Fridman (2:23:22.580)
I hesitate to say this, but this is how I felt,
Matt Walker (2:23:24.700)
which is I needed less sleep.
Lex Fridman (2:23:26.980)
I wonder if my brain is deceiving me
Matt Walker (2:23:28.820)
because it feels like I'm getting
Lex Fridman (2:23:31.020)
a whole extra amount of focus for free.
Lex Fridman (2:23:35.380)
And I wonder if there's longterm impacts of that.
Lex Fridman (2:23:39.660)
Because if I fast 24 hours,
Matt Walker (2:23:42.740)
get the same amount of calories, one meal a day,
Lex Fridman (2:23:45.860)
there's a little bit of discomfort.
Matt Walker (2:23:47.260)
Like just maybe your body gets a little bit colder.
Lex Fridman (2:23:50.500)
Maybe there's just, I mean, hunger.
Lex Fridman (2:23:54.540)
But the amount of focus is crazy.
Lex Fridman (2:23:58.700)
And so I wonder, it's like,
Matt Walker (2:24:00.620)
I'm a little suspicious of that.
Lex Fridman (2:24:02.060)
I feel like I'm getting something for free.
Matt Walker (2:24:04.260)
I'm the same way with sweetener,
Lex Fridman (2:24:06.260)
like a Splendor or something.
Lex Fridman (2:24:07.740)
It's like, it's gotta be really bad for you, right?
Lex Fridman (2:24:10.340)
Because why is it so tasty, right?
Lex Fridman (2:24:12.740)
And I think, yeah, as we said before with biology,
Lex Fridman (2:24:18.580)
if there's a gain, there's often a cost too.
Lex Fridman (2:24:25.180)
But we at least understand the biological basis
Lex Fridman (2:24:28.340)
of what you're describing.
Matt Walker (2:24:29.180)
It's not that you actually don't need less sleep.
Lex Fridman (2:24:33.060)
It's that this chemical is present
Matt Walker (2:24:36.220)
that forces you more awake.
Lex Fridman (2:24:39.140)
And so subjectively you feel as though
Matt Walker (2:24:41.940)
I don't need as much sleep because I'm wide awake.
Lex Fridman (2:24:45.180)
And those two things are quite different.
Matt Walker (2:24:47.820)
It's not as though your sleep need has decreased.
Lex Fridman (2:24:51.740)
It's that your brain has hit the overdrive switch,
Matt Walker (2:24:54.260)
the overboost switch to say, we need to keep you awake
Lex Fridman (2:24:57.500)
because food is in short supply.
Lex Fridman (2:25:00.860)
So you mentioned during sleep, there's a simulation,
Lex Fridman (2:25:03.340)
all those kinds of things for learning purposes,
Lex Fridman (2:25:05.380)
but there's also these, you mentioned the five ways
Lex Fridman (2:25:08.140)
in which we become psychotic in dreams.
Lex Fridman (2:25:11.300)
What do you think dreams are about?
Lex Fridman (2:25:16.260)
Why do you think we dream?
Lex Fridman (2:25:17.700)
What place do we go to when we dream?
Lex Fridman (2:25:21.060)
And why are they useful?
Matt Walker (2:25:22.340)
Not just the assimilation aspect,
Lex Fridman (2:25:25.780)
but just like all the crazy visuals that we get with dreams.
Lex Fridman (2:25:29.460)
Is there something you can speak to that's actually useful?
Lex Fridman (2:25:33.340)
Like why we have such fun experiences in that dream world?
Lex Fridman (2:25:38.340)
So one of the camps in the sleep field
Lex Fridman (2:25:43.260)
is that dreams are meaningless,
Matt Walker (2:25:46.420)
that they are an epiphenomenal byproduct
Lex Fridman (2:25:49.580)
of this thing called REM sleep from which dreams come from
Matt Walker (2:25:53.260)
as a physiological state.
Lex Fridman (2:25:55.380)
So the analogy would be, let's think of a light bulb,
Matt Walker (2:26:00.340)
that the reason that you create the apparatus
Lex Fridman (2:26:02.900)
of a light bulb is to produce this thing called light
Matt Walker (2:26:06.340)
in the same way that we've evolved
Lex Fridman (2:26:08.660)
to this thing called REM sleep
Matt Walker (2:26:10.300)
to serve whatever functions REM sleep serves.
Lex Fridman (2:26:13.700)
But it turns out that when you create light in that way,
Matt Walker (2:26:17.060)
you also produce something called heat.
Lex Fridman (2:26:19.820)
It was never the reason that you designed the light bulb,
Matt Walker (2:26:22.780)
it's just what happens when you create light in that way.
Lex Fridman (2:26:26.140)
And the belief so too was that dreaming
Matt Walker (2:26:29.140)
was essentially the heat of the light bulb.
Lex Fridman (2:26:32.140)
That REM sleep is critical,
Lex Fridman (2:26:34.820)
but when you have REM sleep with a complex brain like ours,
Lex Fridman (2:26:38.340)
you also produce this conscious epiphenomenon called dreaming.
Matt Walker (2:26:44.500)
I don't believe that for a second.
Lex Fridman (2:26:46.140)
And from a simple perspective is that I suspect
Matt Walker (2:26:50.660)
that dreaming is more metabolically costly
Lex Fridman (2:26:54.380)
as a conscious experience than not dreaming.
Lex Fridman (2:26:56.820)
So you could still have REM sleep,
Lex Fridman (2:26:58.580)
but absent the conscious experience of dreaming
Matt Walker (2:27:01.860)
was probably less metabolically costly.
Lex Fridman (2:27:05.540)
And whenever mother nature burns the energy unit
Matt Walker (2:27:08.700)
called ATP, which is the most valuable thing,
Lex Fridman (2:27:13.620)
there's usually a reason for it.
Lex Fridman (2:27:15.220)
So if it's more energetically demanding,
Lex Fridman (2:27:20.340)
then I suspect that there is a function to it.
Lex Fridman (2:27:22.980)
And we've now since discovered that dreams have a function.
Lex Fridman (2:27:26.540)
The first, as we mentioned, creativity.
Matt Walker (2:27:29.100)
The second is that dreams provide a form
Lex Fridman (2:27:32.260)
of overnight therapy.
Matt Walker (2:27:35.060)
Dreaming is a form of emotional first aid.
Lex Fridman (2:27:38.780)
And it's during dream sleep at night
Matt Walker (2:27:40.500)
that we take these difficult, painful experiences
Lex Fridman (2:27:43.820)
that we've had during the day, sometimes traumatic,
Lex Fridman (2:27:46.940)
and dream sleep acts almost like a nocturnal soothing balm.
Lex Fridman (2:27:51.340)
And it sort of just takes the sharp edges
Matt Walker (2:27:53.420)
off those difficult, painful experiences
Lex Fridman (2:27:56.260)
so that you come back the next day
Lex Fridman (2:27:58.580)
and you feel better about them.
Lex Fridman (2:28:01.500)
And so I think in that sense, dreaming,
Matt Walker (2:28:03.940)
it's not time that heals all wounds.
Lex Fridman (2:28:07.260)
It's time during dream sleep
Matt Walker (2:28:09.340)
that provides emotional convalescence.
Lex Fridman (2:28:12.580)
So dreaming is almost a form of emotional windscreen wipers.
Lex Fridman (2:28:19.860)
And I think, and by the way, it's not just that you dream.
Lex Fridman (2:28:24.860)
It's what you dream about that also matters.
Lex Fridman (2:28:30.020)
So for example, scientists have done studies
Lex Fridman (2:28:32.060)
with learning and memory
Matt Walker (2:28:33.020)
where they have people learn a virtual maze.
Lex Fridman (2:28:37.420)
And what they discovered was that those people
Matt Walker (2:28:40.420)
who then dreamed, but dreamed of the maze
Lex Fridman (2:28:45.180)
were the only ones who, when they woke up,
Matt Walker (2:28:47.820)
ended up being better at navigating the maze.
Lex Fridman (2:28:50.740)
Whereas those people who dreamed,
Lex Fridman (2:28:53.380)
but didn't dream about the maze itself,
Lex Fridman (2:28:55.820)
they were no better at navigating the maze.
Lex Fridman (2:28:57.940)
So it's not just that you,
Lex Fridman (2:28:59.060)
it's not sort of necessary, but not sufficient.
Matt Walker (2:29:02.380)
It's necessary that you dream,
Lex Fridman (2:29:04.260)
but it's not sufficient to produce the benefit.
Matt Walker (2:29:06.780)
You have to be dreaming about certain things itself.
Lex Fridman (2:29:09.860)
And the same is true for mental health.
Lex Fridman (2:29:13.300)
What we've discovered is that people
Lex Fridman (2:29:14.740)
who are going through a very difficult experience,
Matt Walker (2:29:17.100)
a trauma, for example, a very painful divorce,
Lex Fridman (2:29:21.140)
those people who are dreaming, but dreaming
Matt Walker (2:29:23.820)
of that difficult event itself,
Lex Fridman (2:29:26.300)
they go on to gain resolution
Matt Walker (2:29:28.540)
to their clinical depression one year later.
Lex Fridman (2:29:31.100)
Whereas people who were dreaming just as much,
Lex Fridman (2:29:34.580)
but not dreaming about the trauma itself,
Lex Fridman (2:29:37.340)
did not go on to gain as much clinical resolution
Matt Walker (2:29:40.700)
to their depression.
Lex Fridman (2:29:42.260)
So it's, I think to me, those are the lines of evidence
Matt Walker (2:29:46.860)
that tell me dreaming is not epiphenomenal.
Lex Fridman (2:29:50.260)
And it's not just about the act of dreaming,
Matt Walker (2:29:53.820)
it's about the content of the dreams,
Lex Fridman (2:29:57.140)
not just the fact of a dream itself.
Matt Walker (2:30:00.420)
It's, first of all, it's fascinating.
Lex Fridman (2:30:01.780)
It makes a lot of sense,
Lex Fridman (2:30:02.900)
but then immediately takes my mind to,
Lex Fridman (2:30:05.540)
from an engineering perspective,
Lex Fridman (2:30:07.100)
how that could be useful in, for example, AI systems of,
Lex Fridman (2:30:13.140)
if you think about dreaming as an important part
Matt Walker (2:30:16.780)
about learning and cognition and filtering previous memories
Lex Fridman (2:30:22.780)
of what's important, integrating them.
Matt Walker (2:30:25.380)
You know, maybe you can correct me,
Lex Fridman (2:30:27.020)
but I see dreaming as a kind of simulation of worlds
Matt Walker (2:30:31.420)
that are not constrained by physics.
Lex Fridman (2:30:34.540)
So like you get a chance to take some of your memories,
Matt Walker (2:30:37.780)
some of your thoughts, some of your anxieties,
Lex Fridman (2:30:40.260)
and play with them, like construct virtual worlds
Lex Fridman (2:30:43.900)
and see how it evolves.
Lex Fridman (2:30:46.540)
Like to play with those worlds
Matt Walker (2:30:48.820)
in a safe environment of your mind, safe in quotes,
Lex Fridman (2:30:51.980)
because you could probably get into a lot of trouble
Matt Walker (2:30:53.740)
with the places your mind will go.
Lex Fridman (2:30:56.900)
But this definitely is applied in much cruder ways
Matt Walker (2:31:04.260)
in artificial intelligence.
Lex Fridman (2:31:05.820)
So one context in which this is applied
Matt Walker (2:31:08.700)
is the process called self play,
Lex Fridman (2:31:12.740)
which is a reinforcement learning
Matt Walker (2:31:14.380)
where agents play against itself or versions of itself.
Lex Fridman (2:31:19.900)
And it's all simulated of trying different versions
Matt Walker (2:31:23.340)
of themselves and playing against each other
Lex Fridman (2:31:25.260)
to see what ends up being a good.
Matt Walker (2:31:29.060)
The ultimate goal is to learn a function
Lex Fridman (2:31:32.580)
that represents what is good and what is not good
Matt Walker (2:31:34.820)
in terms of how you should act in the world.
Lex Fridman (2:31:36.260)
You create a set of decision weights based on experience,
Lex Fridman (2:31:39.420)
and you constantly update those weights
Lex Fridman (2:31:41.500)
based on ongoing learning.
Lex Fridman (2:31:43.020)
But the experience is artificially created
Lex Fridman (2:31:45.940)
versus actual real data.
Lex Fridman (2:31:48.580)
So it's a crude approximation of what dreams are,
Lex Fridman (2:31:51.580)
which is you're hallucinating a lot of things
Matt Walker (2:31:54.380)
to see which things are actually.
Lex Fridman (2:31:56.420)
No, I think it's been a theory that's been put forward,
Matt Walker (2:31:59.300)
which is that dreaming is a virtual reality test space
Lex Fridman (2:32:04.500)
that is largely consequence free.
Lex Fridman (2:32:07.580)
What an incredible gift to give a conscious mind
Lex Fridman (2:32:11.100)
to each and every night.
Matt Walker (2:32:13.260)
Now the conscious mind, the human mind
Lex Fridman (2:32:15.940)
is very good at constructing dreams
Matt Walker (2:32:17.820)
that are nevertheless useful for you.
Lex Fridman (2:32:20.700)
Like they're wild and crazy,
Lex Fridman (2:32:22.580)
but they're such that they are still grounded in reality
Lex Fridman (2:32:27.460)
to a degree where anything you learn in dreams
Matt Walker (2:32:29.980)
might be useful in reality.
Lex Fridman (2:32:32.140)
This is a very difficult thing to do
Matt Walker (2:32:34.420)
because it requires a lot of intelligence,
Lex Fridman (2:32:36.580)
it requires consciousness.
Matt Walker (2:32:38.020)
This has been effectively recently being used
Lex Fridman (2:32:41.700)
in a self supervised learning for computer vision
Matt Walker (2:32:45.980)
with the process of what's called data augmentation.
Lex Fridman (2:32:50.060)
That's a very crude version of dreams,
Matt Walker (2:32:53.260)
which is you take data and you mess with it
Lex Fridman (2:32:56.700)
and you start to learn how a picture of a cat
Matt Walker (2:33:02.660)
truly represents a cat by messing with it in different ways.
Lex Fridman (2:33:06.980)
Now the crude methods currently are cropping, rotating,
Matt Walker (2:33:09.780)
distorting, all that kind of stuff.
Lex Fridman (2:33:11.500)
But you can imagine much more complicated
Matt Walker (2:33:14.980)
generative processes that start hallucinating different cats
Lex Fridman (2:33:19.460)
in order for you to understand deeply of what it means
Matt Walker (2:33:23.140)
for something to look like a cat.
Lex Fridman (2:33:25.060)
What is the prototype of a archetype of a cat?
Matt Walker (2:33:27.660)
Yeah, the archetype.
Lex Fridman (2:33:28.500)
I mean, that's a very difficult process for computer vision
Matt Walker (2:33:31.900)
to go from what are the pixels
Lex Fridman (2:33:36.060)
that are usually associated with a cat
Lex Fridman (2:33:38.500)
to like, what is a cat in the visual space?
Lex Fridman (2:33:42.860)
In the three dimensional visual spaces projected on an image,
Lex Fridman (2:33:46.500)
on a two dimensional image, what is a cat?
Lex Fridman (2:33:50.260)
Those are like fundamentally philosophical questions
Matt Walker (2:33:52.860)
that we humans don't know the answer to,
Lex Fridman (2:33:56.500)
like linguistically.
Lex Fridman (2:33:57.900)
But when we look at a picture of a cat and a dog,
Lex Fridman (2:34:00.900)
we can usually tell pretty damn well what's the difference.
Lex Fridman (2:34:04.300)
And I don't know what that is because you can't reduce that
Lex Fridman (2:34:06.980)
to pointy ears or non pointy ears,
Matt Walker (2:34:09.980)
furry or not furry, something about the eyes.
Lex Fridman (2:34:12.460)
It's been a long standing issue in cognitive science,
Matt Walker (2:34:14.860)
cognitive neuroscience too,
Lex Fridman (2:34:16.620)
is how does the brain create an archetype?
Lex Fridman (2:34:20.180)
How does it create schemas that have general applicability,
Lex Fridman (2:34:26.220)
but yet still obtain specificity?
Matt Walker (2:34:29.700)
That's a very difficult challenge.
Lex Fridman (2:34:31.660)
I mean, we can do it, we do it.
Matt Walker (2:34:33.340)
It's rather bloody amazing.
Lex Fridman (2:34:35.620)
And it seems like part of the toolbox
Matt Walker (2:34:37.700)
is this controlled hallucination, which is dreams.
Lex Fridman (2:34:41.100)
Well, it's a relaxing of the rigid constraints.
Matt Walker (2:34:45.860)
I often think of dreaming as,
Lex Fridman (2:34:48.700)
it's from an information processing standpoint,
Matt Walker (2:34:52.660)
the prison guards are away
Lex Fridman (2:34:54.620)
and the prisoners are running a mock in a delightful way.
Lex Fridman (2:34:58.980)
And part of the reason is because when you go
Lex Fridman (2:35:00.580)
into dream sleep, the rational part of your brain
Matt Walker (2:35:03.580)
called the prefrontal cortex, which is the part,
Lex Fridman (2:35:05.860)
it's like the CEO of the brain.
Matt Walker (2:35:07.620)
It's very good at making high level, rational,
Lex Fridman (2:35:09.500)
top down decisions and controlled actions.
Matt Walker (2:35:12.500)
That part of the brain is shut down during REM sleep.
Lex Fridman (2:35:17.260)
But then emotional centers, memory centers,
Matt Walker (2:35:20.580)
visual centers, motoric centers,
Lex Fridman (2:35:24.140)
all of those centers actually become more active.
Matt Walker (2:35:27.180)
In fact, some of them are more active
Lex Fridman (2:35:29.540)
than when we're awake in the dream state.
Matt Walker (2:35:32.860)
That's fascinating.
Lex Fridman (2:35:33.700)
So your brain from a neural architecture perspective
Matt Walker (2:35:37.300)
is radically different.
Lex Fridman (2:35:39.500)
Its network feature is not the same as wakefulness.
Lex Fridman (2:35:44.460)
And I think this is an immensely beneficial thing
Lex Fridman (2:35:48.100)
that we have at least two different rational
Lex Fridman (2:35:51.700)
and irrational conscious states
Lex Fridman (2:35:54.220)
that we do information processing in.
Matt Walker (2:35:56.420)
The rational, the veritical,
Lex Fridman (2:35:58.180)
the page one of the Google search is wakefulness.
Matt Walker (2:36:01.380)
The more irrational, illogical, hyper associative
Lex Fridman (2:36:05.980)
Google page 20 is the REM sleep.
Matt Walker (2:36:08.620)
Both I think are critical, both are necessary.
Lex Fridman (2:36:11.940)
That's fascinating.
Lex Fridman (2:36:12.780)
And again, fascinating to see how that could be integrated
Lex Fridman (2:36:15.660)
in the machines to help them learn better
Lex Fridman (2:36:18.700)
and to reason better.
Lex Fridman (2:36:22.620)
And in some ways we also know it
Matt Walker (2:36:24.460)
from a chemical perspective too.
Lex Fridman (2:36:25.900)
When you go into dream sleep,
Matt Walker (2:36:27.820)
it is a neurochemical cocktail like no other
Lex Fridman (2:36:31.060)
that we see at the rest of the 24 hour state.
Matt Walker (2:36:34.900)
There is a chemical called noradrenaline
Lex Fridman (2:36:37.700)
or norepinephrine in the brain.
Lex Fridman (2:36:40.380)
And you know of its sister chemical
Lex Fridman (2:36:42.060)
in the body called adrenaline.
Lex Fridman (2:36:44.500)
But upstairs in the brain, noradrenaline
Lex Fridman (2:36:46.900)
is very good at creating a very hyper focused,
Matt Walker (2:36:49.620)
attentive, narrow, it's sort of very convergent way
Lex Fridman (2:36:54.620)
of thinking to a point, sharp focus, that's the only thing.
Matt Walker (2:37:01.180)
The spotlight of consciousness is very narrow.
Lex Fridman (2:37:04.100)
That's noradrenaline.
Matt Walker (2:37:05.820)
When you remove noradrenaline,
Lex Fridman (2:37:08.780)
then you go from a high SNR, a high signal to noise ratio
Matt Walker (2:37:14.380)
where it's just you and I in this moment,
Lex Fridman (2:37:16.860)
I don't even know what's going on elsewhere.
Matt Walker (2:37:18.900)
I am with you, noradrenaline is present.
Lex Fridman (2:37:22.580)
But when you go into REM sleep,
Matt Walker (2:37:24.900)
it is the only time during the 24 hour period
Lex Fridman (2:37:27.180)
where your brain is devoid of any noradrenaline,
Matt Walker (2:37:30.020)
it is completely shut off.
Lex Fridman (2:37:31.700)
And so the signal to noise ratio is very different.
Matt Walker (2:37:34.900)
It's almost as though we're injecting
Lex Fridman (2:37:36.620)
a greater amount of noise into the neural architecture
Matt Walker (2:37:40.180)
of the brain during dream sleep,
Lex Fridman (2:37:42.420)
as if it's chemically brute forced
Matt Walker (2:37:45.740)
into this relaxed associative memory processing state.
Lex Fridman (2:37:50.740)
And then from an anatomical perspective,
Matt Walker (2:37:53.140)
just as I described, the prefrontal cortex goes down
Lex Fridman (2:37:56.180)
and other regions light up.
Lex Fridman (2:37:58.580)
So it is a state that seems to be very,
Lex Fridman (2:38:01.660)
I mean, if you were to show me a brain scan of REM sleep
Lex Fridman (2:38:06.420)
and tell me that it's not REM sleep,
Lex Fridman (2:38:08.820)
just say, look, based on the pattern of this brain activity,
Lex Fridman (2:38:11.620)
what would you say is going on in this person's mind?
Lex Fridman (2:38:14.420)
I would say, well, they're probably not rational.
Matt Walker (2:38:16.500)
They're probably not having logical thought
Lex Fridman (2:38:18.140)
because their prefrontal cortex is down.
Matt Walker (2:38:19.940)
They're probably feeling very emotional
Lex Fridman (2:38:21.460)
because their amygdala is active,
Matt Walker (2:38:23.580)
which is an emotional center of the brain.
Lex Fridman (2:38:25.420)
They're definitely going to be thinking visually
Matt Walker (2:38:27.340)
because the back of the brain is lit up, the visual cortex.
Lex Fridman (2:38:30.620)
It's probably going to be filled with past experience
Lex Fridman (2:38:33.900)
and autobiographical memories
Lex Fridman (2:38:35.940)
because their memory centers are lighting up.
Lex Fridman (2:38:39.540)
And there's probably going to be movement
Lex Fridman (2:38:40.820)
because their motor cortex is very active.
Matt Walker (2:38:43.940)
That to me sounds very much like a dream.
Lex Fridman (2:38:45.940)
And that's exactly what we see in brain scanners
Matt Walker (2:38:48.060)
when we've put people inside of them.
Lex Fridman (2:38:50.420)
One of the things I notice sleep affects
Matt Walker (2:38:54.340)
is my ability to see the beauty in the world.
Lex Fridman (2:39:00.180)
So what do you think is the connection
Matt Walker (2:39:03.700)
between sleep and your emotional life,
Lex Fridman (2:39:06.020)
your ability to love other human beings and love life?
Matt Walker (2:39:10.540)
Yeah, I think it's very powerful and strong.
Lex Fridman (2:39:16.380)
So we've done a lot of work in the field
Matt Walker (2:39:19.020)
of sleep and emotion and sleep and moods.
Lex Fridman (2:39:21.540)
And you can separate your emotions into two main buckets,
Matt Walker (2:39:26.060)
positive and negative.
Lex Fridman (2:39:28.540)
And what's interesting is that when you are sleep deprived
Lex Fridman (2:39:32.020)
and the more hours that you go into being awake
Lex Fridman (2:39:35.540)
and the fewer hours that you've had to sleep,
Matt Walker (2:39:37.980)
your negative mood starts to increase.
Lex Fridman (2:39:43.260)
And we know which individual types
Matt Walker (2:39:46.300)
of emotions are changing.
Lex Fridman (2:39:48.540)
I've got a wonderful postdoc in my lab
Matt Walker (2:39:51.140)
called Etty Ben Simon, who's doing some incredible work
Lex Fridman (2:39:53.980)
on trying to understand the emotional,
Matt Walker (2:39:57.100)
individual emotional tapestry of affective,
Lex Fridman (2:40:02.100)
meltdown when you're not getting sufficient sleep.
Lex Fridman (2:40:07.100)
But let's just keep with two dimensions,
Lex Fridman (2:40:09.180)
positive and negative.
Matt Walker (2:40:10.020)
Yes.
Lex Fridman (2:40:10.860)
Most people would think, well, it's the negative
Matt Walker (2:40:13.460)
that takes the biggest hit when I'm sleep deprived.
Lex Fridman (2:40:15.700)
It's not.
Matt Walker (2:40:17.020)
By probably in a log order, magnitude larger
Lex Fridman (2:40:20.860)
is a hit on your positive emotions.
Matt Walker (2:40:23.900)
In other words, you stop being sleep deprived
Lex Fridman (2:40:27.860)
of positive emotions, in other words, you stop gaining
Matt Walker (2:40:32.900)
pleasure from normally pleasurable things.
Lex Fridman (2:40:35.140)
And it's a state that we call anhedonia.
Lex Fridman (2:40:38.420)
And anhedonia is the state that we often call depression.
Lex Fridman (2:40:43.620)
So depression to most people's surprise isn't necessarily
Matt Walker (2:40:47.300)
that you're always feeling negative emotions.
Lex Fridman (2:40:52.060)
It's often more about the fact that you lose the pleasure
Matt Walker (2:40:56.780)
in the good things in life.
Lex Fridman (2:40:58.700)
That's what we call anhedonia.
Matt Walker (2:41:00.620)
That's what we see in sleep, an insufficient sleep.
Lex Fridman (2:41:03.740)
And it happens quite quickly.
Matt Walker (2:41:05.540)
Yeah, it's kind of fascinating.
Lex Fridman (2:41:06.900)
I think I do, it's not depression,
Lex Fridman (2:41:10.660)
but like it's a stroll into that direction,
Lex Fridman (2:41:15.180)
which is when I'm sleep deprived,
Matt Walker (2:41:17.340)
I stop being able to see the meaning in life.
Lex Fridman (2:41:21.340)
The things that gave me meanings starts to lose meaning.
Matt Walker (2:41:24.980)
Like it makes me realize how enjoyable everything is
Lex Fridman (2:41:29.040)
in my life because when I start to lose it,
Matt Walker (2:41:31.420)
when I'm severely sleep deprived,
Lex Fridman (2:41:33.600)
you start to see how much life sucks when you lose it.
Lex Fridman (2:41:36.060)
But that said, I'm just cognizant enough
Lex Fridman (2:41:38.740)
that sleep fixes all of that.
Lex Fridman (2:41:40.760)
So I use those states for what they're worth.
Lex Fridman (2:41:44.140)
In fact, I personally like to pay attention to the things
Matt Walker (2:41:48.860)
that bother me in doing that time.
Lex Fridman (2:41:52.780)
Cause they also reveal important information to me.
Matt Walker (2:41:58.220)
That's interesting.
Lex Fridman (2:41:59.500)
I have to use like a Rorschach to, yeah.
Matt Walker (2:42:02.220)
I mean, there's, so I find this when I fast combine
Lex Fridman (2:42:05.700)
with sleep deprivation, I'm clear to see with people,
Matt Walker (2:42:10.700)
clear and identifying the things
Lex Fridman (2:42:12.940)
that are not going right in my life
Matt Walker (2:42:15.740)
or people that I'm working with are not doing
Lex Fridman (2:42:19.100)
as good of a job as they could be doing.
Matt Walker (2:42:21.140)
Like people that are negative in my life,
Lex Fridman (2:42:25.940)
I'm more able to identify them.
Lex Fridman (2:42:28.160)
So I don't act on that.
Lex Fridman (2:42:30.020)
It's a very bad time to act on those decisions,
Lex Fridman (2:42:32.340)
but I'm like recording that information
Lex Fridman (2:42:36.860)
because I usually, when I'm well rested and happy,
Matt Walker (2:42:40.040)
I see the beauty in everybody,
Lex Fridman (2:42:42.040)
which can get you into trouble.
Lex Fridman (2:42:44.020)
So you have to balance those two things.
Lex Fridman (2:42:46.020)
But yes, it's fascinating.
Lex Fridman (2:42:47.340)
But there's irony there too, which is the fact that,
Lex Fridman (2:42:50.260)
you know, when you're well rested and well slept,
Matt Walker (2:42:51.980)
just as you said, you see the beauty in life
Lex Fridman (2:42:55.060)
and it sort of enlivens you
Lex Fridman (2:42:56.820)
and sort of gives you a quality of life
Lex Fridman (2:43:01.580)
that's emotionally very different.
Matt Walker (2:43:04.880)
Yet then we are contrasting that against the need
Lex Fridman (2:43:13.300)
for not getting enough sleep
Matt Walker (2:43:15.600)
because of the beautiful things
Lex Fridman (2:43:17.620)
that you want to accomplish in life.
Lex Fridman (2:43:20.480)
And I don't actually see them as,
Lex Fridman (2:43:25.780)
you know, sort of completely counterintuitive
Matt Walker (2:43:29.380)
or paradoxical because I still think that you can strive
Lex Fridman (2:43:32.740)
for all of the brilliant things that you are striving for,
Matt Walker (2:43:35.560)
to have the monumental goals,
Lex Fridman (2:43:38.020)
the Herculean challenges that you wish to take on and solve.
Matt Walker (2:43:43.480)
They can still enthrall you and excite you
Lex Fridman (2:43:46.140)
and stimulate you.
Lex Fridman (2:43:48.020)
But because of the insufficient sleep that they can
Lex Fridman (2:43:52.060)
or that goal can produce,
Matt Walker (2:43:55.420)
it will shave off the beauty of life
Lex Fridman (2:43:59.980)
that you experience in between.
Lex Fridman (2:44:01.300)
And again, this is just about the trade off.
Lex Fridman (2:44:04.100)
I will say though that,
Lex Fridman (2:44:05.200)
and this is not applicable to your circumstance,
Lex Fridman (2:44:11.240)
we do know that insufficient sleep
Matt Walker (2:44:14.380)
is very strongly linked to suicide ideation,
Lex Fridman (2:44:18.720)
suicide attempts and tragically suicide completion as well.
Lex Fridman (2:44:24.160)
And in fact, in 20 years of studying sleep,
Lex Fridman (2:44:28.220)
we have not been able to discover
Matt Walker (2:44:29.780)
a single psychiatric condition in which sleep is normal.
Lex Fridman (2:44:34.700)
And I think that that is a profound,
Matt Walker (2:44:37.380)
I think it tells us so much about the role of sleep
Lex Fridman (2:44:41.860)
as a potential causal agent in psychiatric conditions.
Matt Walker (2:44:45.100)
I also think it's a potential sign
Lex Fridman (2:44:47.620)
that we should be using sleep as a tool
Matt Walker (2:44:50.020)
for the prevention of grave mental illness.
Lex Fridman (2:44:52.260)
Yeah, it's both a cause and a solution.
Lex Fridman (2:44:54.900)
So yeah, I mean, me personally,
Lex Fridman (2:44:57.060)
I've gone through a few dark periods quite recently
Lex Fridman (2:45:01.340)
and it was almost always sleep is not the cause,
Lex Fridman (2:45:06.260)
but sleep is the catalyst from going to a bad time
Matt Walker (2:45:10.820)
to a very bad time.
Lex Fridman (2:45:12.380)
Yeah.
Lex Fridman (2:45:13.220)
And so it's definitely true.
Lex Fridman (2:45:15.080)
And it's funny how sleep can just cure all of that.
Matt Walker (2:45:18.560)
There's actually a beautiful quote
Lex Fridman (2:45:20.080)
by an American entrepreneur called E. Joseph Kosman,
Matt Walker (2:45:24.360)
who once said that the best bridge
Lex Fridman (2:45:26.060)
between despair and hope is a good night's sleep.
Lex Fridman (2:45:30.780)
And I spilled quite so much ink and hundreds of pages
Lex Fridman (2:45:37.140)
in elegantly trying to say the same thing in my book.
Lex Fridman (2:45:40.220)
And he said it in one line and it's beautiful.
Lex Fridman (2:45:43.860)
What do you think is,
Matt Walker (2:45:45.420)
we've been talking about how to extend this life,
Lex Fridman (2:45:47.500)
how to make it a good life.
Matt Walker (2:45:50.140)
We've been talking about love.
Lex Fridman (2:45:53.460)
What do you think is the meaning of this whole ride?
Lex Fridman (2:45:55.840)
Of life?
Lex Fridman (2:45:56.680)
Of life.
Lex Fridman (2:45:57.500)
Why do we wanna make it a good one?
Lex Fridman (2:46:00.800)
Do you think there's a meaning?
Lex Fridman (2:46:01.860)
Do you think there's a answer to the why?
Lex Fridman (2:46:05.700)
For me personally,
Matt Walker (2:46:06.880)
I think the meaning of life is to eat,
Lex Fridman (2:46:15.120)
is to sleep, is to fall in love, is to cry,
Lex Fridman (2:46:22.840)
and then to die.
Lex Fridman (2:46:27.300)
Oh, and probably race cars in between.
Matt Walker (2:46:29.760)
Race cars.
Lex Fridman (2:46:30.600)
Well, there's a whole topic of sex we didn't talk about.
Lex Fridman (2:46:33.400)
So that's probably in there.
Lex Fridman (2:46:34.880)
Should we do that?
Matt Walker (2:46:35.720)
Maybe if you'll have me back, I would love to do.
Lex Fridman (2:46:38.920)
I will go around to.
Matt Walker (2:46:39.760)
Next time we will do another three hours on sex alone.
Lex Fridman (2:46:42.760)
Has it been?
Matt Walker (2:46:43.600)
Yeah.
Lex Fridman (2:46:44.440)
It has been over three hours.
Matt Walker (2:46:46.800)
Gosh, okay.
Lex Fridman (2:46:47.640)
Matt, I'm a big fan of your work.
Matt Walker (2:46:50.320)
I think you're doing really important work.
Lex Fridman (2:46:51.960)
Even despite all the things I've been saying
Matt Walker (2:46:54.240)
about the madness of my own sleep schedule,
Lex Fridman (2:46:56.600)
I think you're helping millions of people.
Lex Fridman (2:46:58.720)
So it's an honor that you spend your valuable time with me
Lex Fridman (2:47:02.280)
and I can't wait until your podcast comes out.
Matt Walker (2:47:05.760)
I'm a huge fan of podcasts, I'm a huge fan of you,
Lex Fridman (2:47:08.280)
and it's just an honor to know you
Lex Fridman (2:47:10.840)
and to get a chance, hopefully in the future,
Lex Fridman (2:47:12.520)
to work together with you.
Matt Walker (2:47:13.760)
You're a brilliant man and you're doing amazing things.
Lex Fridman (2:47:17.360)
And I feel immensely honored to have met you,
Matt Walker (2:47:22.240)
to now know you, and to start calling you a friend.
Lex Fridman (2:47:25.880)
Thank you for what you do for the world
Lex Fridman (2:47:27.680)
and for me included.
Lex Fridman (2:47:32.320)
Thank you, Matt.
Matt Walker (2:47:33.160)
Take care.
Lex Fridman (2:47:34.640)
Thanks for listening to this conversation with Matt Walker
Lex Fridman (2:47:37.080)
and thank you to Stamps.com, Squarespace,
Lex Fridman (2:47:40.720)
Letter Greens, BetterHelp, and Onnit.
Matt Walker (2:47:43.560)
Check them out in the description to support this podcast.
Lex Fridman (2:47:46.960)
And now, let me leave you with some words
Matt Walker (2:47:49.160)
from Nikola Tesla, who we discussed in this podcast
Lex Fridman (2:47:52.280)
as sleeping very few hours a night.
Matt Walker (2:47:54.120)
All that was great in the past was ridiculed,
Lex Fridman (2:47:57.600)
condemned, combated, and suppressed,
Matt Walker (2:48:00.160)
only to emerge all the more powerfully,
Lex Fridman (2:48:02.760)
all the more triumphantly from the struggle.
Matt Walker (2:48:05.440)
Thank you for listening and hope to see you next time.
Lex Fridman (30:00.100)
that are so embryonic because, you know,
Matt Walker (30:03.220)
I suspect it's the same with you.
Lex Fridman (30:05.620)
Answers to me are simply ways to get to more questions.
Matt Walker (30:09.820)
You know, it's questions where, you know,
Lex Fridman (30:12.140)
questions turn me on, answers less so.
Lex Fridman (30:15.020)
And I love the fact that we are still embryonic
Lex Fridman (30:18.820)
in our sense of arguing about
Matt Walker (30:20.940)
even what the definition of consciousness is.
Lex Fridman (30:23.780)
But I also find it fascinating.
Matt Walker (30:25.660)
I think it's thoroughly delightful
Lex Fridman (30:27.660)
to absorb yourself in the thought.
Matt Walker (30:30.140)
Think about the brain and we can move back
Lex Fridman (30:33.780)
across the complexity of phylogeny
Matt Walker (30:35.940)
from, you know, humans to mammals
Lex Fridman (30:38.100)
to sort of birds to reptiles, amphibians, fish.
Matt Walker (30:41.980)
You can, bacteria, whatever you want.
Lex Fridman (30:44.900)
And you can go through this and say, okay,
Matt Walker (30:46.700)
where is the hard line of, you know,
Lex Fridman (30:48.700)
what we would define as consciousness?
Lex Fridman (30:51.220)
And I'm sure it's got something to do
Lex Fridman (30:52.820)
with the complexity of the neural system.
Matt Walker (30:55.300)
Of that, I'm fairly certain.
Lex Fridman (30:57.540)
But to me, it's always been fascinating.
Lex Fridman (31:01.380)
So what is it then?
Lex Fridman (31:02.500)
You know, is it that I just keep adding neurons
Matt Walker (31:04.620)
to a Petri dish and I just keep adding them
Lex Fridman (31:07.180)
and adding them and adding them.
Matt Walker (31:08.260)
At some point when I hit a critical mass
Lex Fridman (31:10.260)
of interconnected neurons, that is the mass of the,
Matt Walker (31:13.180)
you know, the interconnected human brain, then bingo.
Lex Fridman (31:17.620)
All of a sudden it kicks into gear
Lex Fridman (31:19.780)
and we have consciousness.
Lex Fridman (31:21.300)
Like a phase shift, phase transition of some kind.
Matt Walker (31:23.540)
Correct, yeah.
Lex Fridman (31:24.460)
But there is something about the complexity
Matt Walker (31:26.260)
of the nervous system that I think
Lex Fridman (31:27.940)
is fundamental to consciousness.
Lex Fridman (31:29.260)
And the reason I bring that up is because
Lex Fridman (31:31.420)
when we're trying to then think about creating it
Matt Walker (31:33.700)
in an artificial way, does that inform us
Lex Fridman (31:36.780)
as to the complexity that we should be looking at
Lex Fridman (31:39.220)
in terms of development?
Lex Fridman (31:41.300)
I also think that it's a missed opportunity
Matt Walker (31:44.420)
in the sort of digital space for us
Lex Fridman (31:48.620)
to try to recreate human consciousness.
Matt Walker (31:52.260)
We've already got human consciousness.
Lex Fridman (31:54.700)
What if we were to think about creating
Matt Walker (31:57.460)
some other form of, why do we have to think
Lex Fridman (31:59.900)
that the ultimate in the creation of, you know,
Matt Walker (32:03.620)
an artificial intelligence is the replication,
Lex Fridman (32:07.380)
you know, of a human state of consciousness?
Matt Walker (32:11.900)
Can we not think outside of our own consciousness
Lex Fridman (32:16.660)
and believe that there is something even more incredible
Lex Fridman (32:19.340)
or more complimentary, more orthogonal?
Lex Fridman (32:24.220)
So I'm sometimes perplexed that people
Matt Walker (32:28.420)
are trying to mimic human consciousness
Lex Fridman (32:30.540)
rather than think about creating
Matt Walker (32:33.180)
something that's different.
Lex Fridman (32:34.980)
I think of human consciousness or consciousness in general
Matt Walker (32:37.780)
as this magic superpower that allows us
Lex Fridman (32:42.820)
to deeply experience the world.
Lex Fridman (32:44.740)
And just as you're saying, I don't think that superpower
Lex Fridman (32:47.260)
has to take the exact flavor as humans have.
Matt Walker (32:49.780)
That's my love for robots.
Lex Fridman (32:51.860)
I would love to add the ability to robots
Matt Walker (32:56.180)
that can experience the world and other humans deeply.
Lex Fridman (33:01.780)
I'm humbled by the fact that that idea
Matt Walker (33:04.060)
does not necessarily need to look anything like
Lex Fridman (33:06.940)
how humans experience the world.
Lex Fridman (33:09.300)
But there's a dance of human to robot connection
Lex Fridman (33:14.780)
the same way human to dog or human to cat connection,
Matt Walker (33:18.500)
that there's a magic there to that interaction.
Lex Fridman (33:21.820)
And I'm not sure how to create that magic,
Lex Fridman (33:23.580)
but it's a worthy effort.
Lex Fridman (33:25.100)
I also love, just exactly as you said,
Matt Walker (33:27.940)
on the question of consciousness
Lex Fridman (33:29.420)
or engineering consciousness,
Matt Walker (33:31.060)
the fun thing about this problem
Lex Fridman (33:34.980)
is it seems obvious to me that a hundred years from now,
Matt Walker (33:38.860)
no matter what we do today,
Lex Fridman (33:41.340)
people, if we're still here,
Matt Walker (33:43.340)
will laugh at how silly our notions were.
Lex Fridman (33:47.340)
So like, it's almost impossible for me to imagine
Matt Walker (33:49.900)
that we will truly solve this problem fully in my lifetime.
Lex Fridman (33:56.340)
And more than that,
Matt Walker (33:57.780)
everything we'll do will be silly a hundred years from now,
Lex Fridman (34:02.620)
but it's still, that makes it fun to me
Matt Walker (34:05.660)
because it's like you have the full freedom
Lex Fridman (34:07.940)
to not even be right, just to try.
Matt Walker (34:11.260)
Just to try is freedom.
Lex Fridman (34:13.100)
And that's how I see that.
Matt Walker (34:15.460)
Get me that T shirt, please.
Lex Fridman (34:17.780)
I love that.
Matt Walker (34:18.660)
So, and human robot interaction is fascinating
Lex Fridman (34:22.100)
because it's like watching dancing.
Matt Walker (34:24.260)
I've been dancing tango recently
Lex Fridman (34:28.340)
and just, it's like, there is no goal.
Matt Walker (34:31.100)
The goal is to create something magical
Lex Fridman (34:33.820)
and whether consciousness or emotion
Matt Walker (34:37.620)
or elegance of movement,
Lex Fridman (34:39.220)
all of those things aid in the creation of the magic.
Lex Fridman (34:43.380)
And it's a free, it's an art form to explore
Lex Fridman (34:46.060)
how to make that, how to create that
Matt Walker (34:49.900)
in a way that's compelling.
Lex Fridman (34:51.260)
Yeah, I love the line in Sense of a Woman with Al Pacino
Matt Walker (34:54.420)
where he's speaking about the tango
Lex Fridman (34:55.980)
and he said, really, it's just freedom
Matt Walker (34:57.740)
that if you get tangled up, you just keep tangoing on.
Lex Fridman (35:01.900)
I still, to this day, I think first or second time
Matt Walker (35:06.420)
I talked to Joe Rogan on his podcast,
Lex Fridman (35:08.900)
I said, we got into this heated argument
Matt Walker (35:11.540)
about whether Sense of a Woman
Lex Fridman (35:13.980)
is a better movie than John Wick.
Matt Walker (35:16.780)
Because it's one of my favorite movies for many reasons.
Lex Fridman (35:20.300)
One is Sense of a Woman.
Matt Walker (35:23.860)
Partially.
Lex Fridman (35:24.700)
I didn't know that, by the way.
Matt Walker (35:25.540)
I was just gonna.
Lex Fridman (35:26.380)
You just.
Matt Walker (35:27.220)
Yeah, I didn't know if you would actually know
Lex Fridman (35:28.220)
of the movie.
Matt Walker (35:29.060)
Awesome, awesome.
Lex Fridman (35:29.900)
No, yeah, I said, I love the tango scene.
Matt Walker (35:31.900)
I love Al Pacino's performance.
Lex Fridman (35:34.660)
It's a wonderful movie.
Matt Walker (35:36.900)
Then Joe was saying, John Wick is better.
Lex Fridman (35:39.380)
So we, to this day, argue about this.
Matt Walker (35:41.460)
I think it depends on what conscious state you're in
Lex Fridman (35:44.980)
that you would be ready and receptive to.
Lex Fridman (35:46.980)
But Sense of a Woman, I think it has one of the best
Lex Fridman (35:50.460)
monologues at the end of the movie
Matt Walker (35:52.740)
that has ever been written or at least performed.
Lex Fridman (35:57.020)
When Al Pacino defends the younger.
Matt Walker (36:01.940)
Yeah, I often think about that.
Lex Fridman (36:05.900)
There's been times in my life, I don't know about you,
Matt Walker (36:09.940)
where I wish I had an Al Pacino in my life,
Lex Fridman (36:12.540)
where integrity is really important in this life.
Matt Walker (36:18.260)
It is.
Lex Fridman (36:19.100)
And sometimes you find yourself in places
Matt Walker (36:20.780)
where there's pressure to sacrifice that integrity.
Lex Fridman (36:25.560)
And you want, what is it, Lieutenant Colonel
Matt Walker (36:29.140)
or whatever he was.
Lex Fridman (36:30.820)
To come in.
Matt Walker (36:31.660)
Slate.
Lex Fridman (36:32.500)
To come in on your side and scream at everyone
Lex Fridman (36:36.140)
and say, what the hell are we doing here?
Lex Fridman (36:38.500)
Being, you know, unfortunately British
Lex Fridman (36:41.260)
and sort of having that slightly awkward
Lex Fridman (36:44.340)
sort of Hugh Grant gene.
Matt Walker (36:45.420)
It's very, very, very at the opposite end of the spectrum
Lex Fridman (36:48.820)
of the remarkable feat of Al Pacino
Matt Walker (36:51.820)
at the end of that scene.
Lex Fridman (36:53.060)
But, and yeah, integrity is, it's a challenging thing
Lex Fridman (36:59.160)
and I value it much.
Lex Fridman (37:00.300)
And I think it can take 20 years to build a reputation
Lex Fridman (37:04.900)
and two minutes to lose it.
Lex Fridman (37:06.580)
And there is nothing more that I value than that integrity
Matt Walker (37:10.420)
and, you know, if I'm ever wrong about anything,
Lex Fridman (37:13.580)
I truly don't want to be wrong for any longer
Matt Walker (37:16.860)
than I have to be.
Lex Fridman (37:19.420)
You know, that's what being in some ways a scientist is.
Matt Walker (37:22.700)
You're just driven by truth.
Lex Fridman (37:25.460)
And the irony relative to something like mathematics
Matt Walker (37:29.200)
is that in science, you never find truth.
Lex Fridman (37:31.900)
What you do in science is you discount the things
Matt Walker (37:35.460)
that are likely to be untrue,
Lex Fridman (37:38.020)
leaving only the possibility of what could be true.
Lex Fridman (37:42.220)
But in math, you know, when you create, you know, a proof,
Lex Fridman (37:46.620)
it's a proof for, you know, from that point forward,
Matt Walker (37:51.820)
there is truth in mathematics.
Lex Fridman (37:54.300)
And there's, I think there's a beauty in that,
Lex Fridman (37:56.980)
but I kind of like the messiness of science
Lex Fridman (38:00.180)
because again, to me, it's less about the truth
Matt Walker (38:03.600)
of the answer and it is more about the pursuit of questions.
Lex Fridman (38:07.220)
But their integrity becomes more and more important
Lex Fridman (38:10.100)
and it becomes more difficult.
Lex Fridman (38:11.800)
There's a lot of pressures,
Matt Walker (38:12.980)
just like in the rest of the world,
Lex Fridman (38:14.100)
but there's a lot of pressures than a scientist.
Matt Walker (38:17.180)
One is like funding sources.
Lex Fridman (38:19.420)
I've noticed this, that, you know,
Matt Walker (38:21.360)
money affects everyone's mind, I think.
Lex Fridman (38:24.580)
I've been always somebody that I believe money can't,
Matt Walker (38:28.320)
you can't buy my opinion.
Lex Fridman (38:31.480)
I don't care how much money, billions or trillions.
Lex Fridman (38:34.380)
But that pressure is there and you have to be
Lex Fridman (38:37.460)
very cognizant of it and make sure that your opinion
Matt Walker (38:40.900)
is not defined by the funding sources.
Lex Fridman (38:43.380)
And then the other is just your own success of, you know,
Matt Walker (38:48.260)
for a couple of decades, publishing an idea
Lex Fridman (38:53.860)
and then realizing at some point
Matt Walker (38:55.460)
that that idea was wrong all along.
Lex Fridman (38:57.860)
And that's a tough thing for people to do,
Lex Fridman (39:00.800)
but that's also integrity is to walk away,
Lex Fridman (39:03.200)
is to say that you were wrong.
Matt Walker (39:06.180)
That doesn't have to be in some big dramatic way.
Lex Fridman (39:08.860)
It could be in a bunch of tiny ways along the way.
Matt Walker (39:11.860)
Right.
Lex Fridman (39:12.700)
Like reconfigure your intuition about a particular problem.
Matt Walker (39:18.800)
That's, and all of that is integrity.
Lex Fridman (39:20.520)
When everybody in the room, you know,
Matt Walker (39:23.460)
believes a certain thing,
Lex Fridman (39:24.500)
everybody in the community believes a certain thing,
Matt Walker (39:27.440)
to be able to still be open minded in the face of that.
Lex Fridman (39:31.000)
Yeah, and I think it comes down in some ways
Matt Walker (39:33.820)
to the issue of ego that you bond your correctness
Lex Fridman (39:38.980)
or your rightness, your scientific theory
Matt Walker (39:41.820)
with your sense of ego.
Lex Fridman (39:45.820)
You know, I've never found it that difficult to let go
Matt Walker (39:48.740)
of theories in the face of counter evidence
Lex Fridman (39:52.780)
in part because I have such low self esteem.
Matt Walker (39:56.380)
Well, I kind of liked that.
Lex Fridman (39:57.900)
I always liked that combination.
Matt Walker (39:59.020)
I have the same, I'm like very self critical,
Lex Fridman (40:01.620)
imposter syndrome, all those things,
Matt Walker (40:04.500)
putting yourself below the podium,
Lex Fridman (40:05.740)
but at the same time having the ego
Matt Walker (40:08.140)
that drives the ambition to work your ass off.
Lex Fridman (40:11.060)
Like some kind of weird drive,
Matt Walker (40:13.520)
maybe like drive to be better.
Lex Fridman (40:16.740)
Like thinking of yourself as not that great
Lex Fridman (40:18.940)
and always driving to be better.
Lex Fridman (40:20.940)
And then at the same time,
Matt Walker (40:22.020)
because that can be paralyzing and exhausting and so on,
Lex Fridman (40:25.940)
at the same time, just being grateful to be alive.
Lex Fridman (40:28.360)
But in the sciences, in the actual effort,
Lex Fridman (40:31.340)
never be satisfied, never think of yourself highly.
Matt Walker (40:33.940)
It seems to be a nice combination.
Lex Fridman (40:35.860)
I very much hope that that is part of who I am
Lex Fridman (40:39.700)
and I remain very quietly motivated and driven.
Lex Fridman (40:44.420)
And I, like you, love the idea of perfection
Lex Fridman (40:47.980)
and I know I will never achieve it,
Lex Fridman (40:49.700)
but I will never stop trying to.
Lex Fridman (40:52.220)
So similar to you, which sounds weird
Lex Fridman (40:55.500)
because there's all these videos of me on the internet.
Lex Fridman (41:01.060)
So I think I just naturally lean into the things
Lex Fridman (41:04.400)
I'm afraid of and I'm uncomfortable doing.
Matt Walker (41:07.020)
Like I'm very afraid of talking to people
Lex Fridman (41:09.120)
and just even before talking to you today,
Matt Walker (41:12.700)
just a lot of anxiety and all those kinds of things.
Lex Fridman (41:16.100)
About talking to me?
Matt Walker (41:17.540)
Yeah, yeah.
Lex Fridman (41:18.380)
Oh, I like.
Matt Walker (41:19.200)
Nervousness.
Lex Fridman (41:20.940)
Fear in some cases, self doubt and all those kinds of things.
Lex Fridman (41:24.540)
But I do it anyway.
Lex Fridman (41:25.980)
So the reason I bring that up
Matt Walker (41:27.480)
is you've launched a podcast.
Lex Fridman (41:32.120)
I have.
Matt Walker (41:34.540)
Allow me to say, I think you're a great science communicator.
Lex Fridman (41:37.360)
So this challenge of being afraid
Matt Walker (41:44.180)
or cautious of being in the public eye
Lex Fridman (41:47.980)
and yet having a longing to communicate
Matt Walker (41:51.420)
some of the things you're excited about
Lex Fridman (41:53.620)
in the space of sleep and beyond.
Lex Fridman (41:55.900)
What's your vision with this project?
Lex Fridman (41:59.180)
I think firstly to that question, like you,
Matt Walker (42:03.620)
I am always more afraid of not trying than trying.
Lex Fridman (42:07.980)
Yeah.
Matt Walker (42:08.820)
That to me frightens me more.
Lex Fridman (42:12.040)
But with the podcast,
Matt Walker (42:13.500)
I think really I have two very simple goals.
Lex Fridman (42:18.660)
I want to try and democratize the science of sleep
Lex Fridman (42:22.980)
and in doing so,
Lex Fridman (42:23.820)
my goal would be to try and reunite humanity
Matt Walker (42:26.420)
with the sleep that it is so desperately bereft of.
Lex Fridman (42:30.540)
And if I can do that through a number of different means,
Matt Walker (42:35.480)
the podcast is a little bit different than this format.
Lex Fridman (42:38.500)
It's going to be short form monologues from yours truly
Matt Walker (42:45.180)
that will last usually less than just 10 minutes.
Lex Fridman (42:47.780)
And I see it as simply a little slice of sleep goodness
Matt Walker (42:51.420)
that can accompany your waking day.
Lex Fridman (42:53.940)
It's hard to know what is the right way
Matt Walker (42:56.380)
to do science communication.
Lex Fridman (42:58.440)
Like your friend, mine, Andrew Huberman,
Matt Walker (43:03.660)
he's an incredible human being.
Lex Fridman (43:05.460)
Oh gosh.
Lex Fridman (43:06.300)
So he does like two hours of,
Lex Fridman (43:09.420)
I wonder how many takes he does.
Matt Walker (43:10.660)
I don't know, but it looks like he doesn't do any.
Lex Fridman (43:12.820)
Yeah, I suspect he's that magnificent of a human being.
Matt Walker (43:16.300)
When I talk to him in like in person,
Lex Fridman (43:18.940)
he always generates intelligent words,
Matt Walker (43:21.580)
well cited, nonstop for hours.
Lex Fridman (43:24.180)
So I don't.
Matt Walker (43:25.700)
He's a Gatling gun of information and it's pristine.
Lex Fridman (43:29.020)
And passion and all those kinds of things.
Lex Fridman (43:30.700)
So that's an interesting medium.
Lex Fridman (43:32.220)
I wouldn't have,
Matt Walker (43:35.260)
it's funny because I wouldn't have done it
Lex Fridman (43:36.780)
the way he's doing it.
Matt Walker (43:38.020)
I wouldn't advise him to do it the way he's doing it.
Lex Fridman (43:40.340)
Cause I thought there's no way you could do
Lex Fridman (43:41.740)
what you're doing.
Lex Fridman (43:43.860)
Cause it's a lot of work,
Lex Fridman (43:45.540)
but he is like doing an incredible job of it.
Lex Fridman (43:48.420)
I just think it's the same with like Dan Carlin
Lex Fridman (43:51.060)
and hardcore history.
Lex Fridman (43:52.140)
I thought that the way Andrew's doing it
Matt Walker (43:56.700)
would crush him the way it crushes Dan Carlin.
Lex Fridman (44:00.860)
So Dan has so much pressure on him to do a good job
Matt Walker (44:04.660)
that he ends up publishing like two episodes a year.
Lex Fridman (44:08.140)
So that pressure can be paralyzing.
Matt Walker (44:10.100)
The pressure of like putting out like
Lex Fridman (44:13.580)
strong scientific statements
Matt Walker (44:16.140)
that can be overwhelming.
Lex Fridman (44:17.820)
Now, Andrew seems to be just plowing through anyway.
Matt Walker (44:21.540)
If there's mistakes, he'll say there's corrections and so on.
Lex Fridman (44:25.220)
I just, I wonder,
Matt Walker (44:26.220)
I actually haven't talked to him too much about it.
Lex Fridman (44:27.900)
Like psychologically, how difficult is it
Matt Walker (44:30.820)
to put yourself out there for an hour to a week
Lex Fridman (44:34.700)
of just nonstop dropping knowledge.
Matt Walker (44:37.980)
Any one sentence of which could be totally wrong.
Lex Fridman (44:41.140)
It could be a mistake.
Lex Fridman (44:42.300)
And there will be mistakes.
Lex Fridman (44:44.260)
And I, in the first edition of my book,
Matt Walker (44:47.460)
there were errors that we corrected
Lex Fridman (44:50.020)
in the second edition too.
Lex Fridman (44:52.420)
But there will be probabilistically,
Lex Fridman (44:55.860)
if you've got 10 facts per page of a book
Lex Fridman (44:59.100)
and you've got 350 pages,
Lex Fridman (45:02.500)
odds are it's probably not going to be
Matt Walker (45:05.260)
utter perfection out the gate.
Lex Fridman (45:07.420)
And it will be the same way for Andrew too.
Lex Fridman (45:11.780)
But having the reverence of
Lex Fridman (45:15.620)
a humble mind
Lex Fridman (45:19.380)
and simply accepting the things that are wrong
Lex Fridman (45:21.940)
and correcting them and doing the right thing.
Matt Walker (45:23.900)
I know that that's his mentality.
Lex Fridman (45:26.620)
I do want to say that I'm just kind of honored to be,
Matt Walker (45:30.260)
it's a cool group of like scientific people
Lex Fridman (45:34.780)
that I'm fortunate enough to now be interacting with.
Matt Walker (45:38.060)
It's you and Andrew and David Sinclair
Lex Fridman (45:41.180)
has been thinking about throwing his hat in the ring.
Matt Walker (45:43.100)
Oh, I hope so.
Lex Fridman (45:43.940)
David is another one of those very special people
Matt Walker (45:46.740)
in the world.
Lex Fridman (45:47.580)
So it's cool because podcasts are, it's cool.
Matt Walker (45:51.100)
It's such a powerful medium of communication.
Lex Fridman (45:53.460)
It's much freer than more constrained
Matt Walker (45:56.540)
like publications and so on.
Lex Fridman (45:58.420)
Or it's much more accessible and inspiring than like,
Matt Walker (46:01.860)
I don't know, conference presentations or lectures.
Lex Fridman (46:04.020)
And so it's a really exciting medium to me.
Lex Fridman (46:06.900)
And it's cool that there's this like group of people
Lex Fridman (46:08.860)
that are becoming friends and putting stuff out there
Lex Fridman (46:12.700)
and supporting each other.
Lex Fridman (46:13.660)
So it's fun to also watch how that's going to evolve
Matt Walker (46:18.140)
in your case, because I wonder it'll be two a month.
Lex Fridman (46:20.860)
Or devolve is the answer to that.
Matt Walker (46:24.980)
Well, I mean, some of it is persistence
Lex Fridman (46:27.700)
through the challenges that we've been talking about,
Matt Walker (46:30.220)
which is like.
Lex Fridman (46:31.060)
I think I've got a lot to learn.
Matt Walker (46:32.460)
Yeah.
Lex Fridman (46:33.300)
But I will persist.
Lex Fridman (46:35.700)
Can I ask you some detailed stuff?
Lex Fridman (46:37.460)
You mentioned that.
Matt Walker (46:38.300)
Oh my goodness, go anywhere you wish with sleep.
Lex Fridman (46:41.620)
So I'm a big fan of coffee and caffeine.
Lex Fridman (46:45.300)
And I've been, especially in the last few days,
Lex Fridman (46:47.820)
consuming a very large amount.
Lex Fridman (46:50.140)
And I'm cognizant of the fact that my body is affected
Lex Fridman (46:55.660)
by caffeine different than the anecdotal information
Matt Walker (46:59.020)
that other people tell me.
Lex Fridman (47:00.740)
I seem to be not at all affected by it.
Matt Walker (47:03.900)
It's almost, it feels like more like a ritual
Lex Fridman (47:08.900)
than it is a chemical boost to my performance.
Matt Walker (47:12.140)
Like I can drink several cups of coffee right before bed
Lex Fridman (47:15.380)
and just knock out anyway.
Matt Walker (47:17.740)
I'm not sure if it's a biological chemical
Lex Fridman (47:20.220)
or it has to do with just the fact
Matt Walker (47:21.540)
that I'm consuming huge amounts of caffeine.
Lex Fridman (47:24.340)
All that to say, what do you think is the relationship
Lex Fridman (47:29.540)
between coffee and sleep, caffeine and sleep?
Lex Fridman (47:32.900)
If there's an interesting distinction there.
Matt Walker (47:34.380)
There is a distinction.
Lex Fridman (47:35.660)
So I think the first thing to say,
Matt Walker (47:37.580)
which is going to sound strange coming from me
Lex Fridman (47:40.180)
is drink coffee.
Matt Walker (47:43.540)
The health benefits associated with drinking coffee
Lex Fridman (47:46.460)
are really quite well established now.
Lex Fridman (47:51.140)
But I think that the counterpoint to that,
Lex Fridman (47:54.180)
well, firstly, the dose and the timing make the poison.
Lex Fridman (47:57.860)
And I'll perhaps come back to that in just a second.
Lex Fridman (48:01.220)
But for coffee, it's actually not the caffeine.
Matt Walker (48:06.220)
So, a lot of people have asked me
Lex Fridman (48:09.620)
about this rightful paradox between the fact
Matt Walker (48:12.140)
that sleep provides all of these incredible health benefits
Lex Fridman (48:15.580)
and then coffee, which can have a deleterious impact
Matt Walker (48:19.460)
on your sleep has a whole collection of health benefits.
Lex Fridman (48:23.020)
Many of them Venn diagram overlapping
Matt Walker (48:25.460)
with those that sleep provides.
Lex Fridman (48:27.380)
How on earth can you reconcile those two?
Lex Fridman (48:30.220)
And the answer is that, well, the answer is very simple.
Lex Fridman (48:33.740)
It's called antioxidants, that it turns out
Matt Walker (48:37.780)
that for most people in Western civilization
Lex Fridman (48:40.820)
because of diet, not being quite what it should be,
Matt Walker (48:44.940)
the major source through which they obtain antioxidants
Lex Fridman (48:49.300)
is the coffee bean.
Lex Fridman (48:50.380)
So the humble coffee bean has now been asked
Lex Fridman (48:53.700)
to carry the astronomical weight of serving up
Matt Walker (48:57.580)
the large majority of people's antioxidant needs.
Lex Fridman (49:01.900)
And you can see this if, for example,
Matt Walker (49:04.820)
you look at the health benefits of decaffeinated coffee,
Lex Fridman (49:08.340)
it has a whole constellation
Matt Walker (49:10.260)
of really great health benefits too.
Lex Fridman (49:12.100)
So it's not the caffeine.
Lex Fridman (49:13.420)
And that's why I liked what you said,
Lex Fridman (49:15.300)
this sort of separation of church and state
Matt Walker (49:17.740)
between coffee and caffeine.
Lex Fridman (49:19.900)
It's not the caffeine, it's the coffee bean itself
Matt Walker (49:23.340)
that provides those health benefits.
Lex Fridman (49:24.820)
But coming back to how it impacts sleep,
Matt Walker (49:29.620)
it impacts sleep in probably at least three different ways.
Lex Fridman (49:33.540)
The first is that for most people,
Matt Walker (49:37.060)
caffeine can make it obviously a little harder
Lex Fridman (49:39.460)
to fall asleep.
Matt Walker (49:41.140)
Caffeine can make it harder to stay asleep.
Lex Fridman (49:44.060)
But let's say that you are one of those individuals
Lex Fridman (49:46.100)
and I think you are, and you can say,
Lex Fridman (49:48.060)
look, I can have three or four espressos with dinner
Lex Fridman (49:50.700)
and I fall asleep just fine
Lex Fridman (49:52.300)
and I stay asleep soundly across the night.
Lex Fridman (49:54.500)
So there's no problem.
Lex Fridman (49:56.220)
The downside there is that even if that is true,
Matt Walker (50:00.300)
the amount of deep sleep that you get will not be as deep.
Lex Fridman (50:03.820)
And so you will actually lose somewhere
Matt Walker (50:05.500)
between 10 to 30% of your deep sleep
Lex Fridman (50:08.500)
if you drink caffeine in the evening.
Lex Fridman (50:11.300)
So to give you some context,
Lex Fridman (50:12.940)
to drop your deep sleep by let's say 20%,
Matt Walker (50:16.460)
I'd probably have to age you by 15 years,
Lex Fridman (50:19.260)
or you could do it every night with a cup of coffee.
Matt Walker (50:22.540)
I think the fourth component
Lex Fridman (50:24.140)
that is perhaps less well understood about coffee
Matt Walker (50:27.140)
is its timing, and that's why I was saying
Lex Fridman (50:29.660)
the timing and the dose make the poison.
Matt Walker (50:31.580)
The dose, by the way,
Lex Fridman (50:32.900)
once you get past about three cups of coffee a day,
Matt Walker (50:35.820)
the health benefits actually start to turn down
Lex Fridman (50:38.420)
in the opposite direction.
Lex Fridman (50:40.220)
So there is a U shape function.
Lex Fridman (50:41.980)
It's sort of the Goldilocks syndrome,
Matt Walker (50:44.220)
not too little, not too much, just the right amount.
Lex Fridman (50:47.980)
The second component is the timing though.
Matt Walker (50:50.700)
Caffeine has half life of about five to six hours,
Lex Fridman (50:55.220)
meaning that after five to six hours,
Matt Walker (50:57.820)
50% of that on average for the average adult
Lex Fridman (51:01.140)
is still in the system,
Matt Walker (51:02.500)
which means that it has a quarter life of 10 to 12 hours.
Lex Fridman (51:06.020)
So in other words, if you have a coffee at noon,
Matt Walker (51:08.260)
a quarter of that caffeine is still circulating
Lex Fridman (51:10.580)
in your brain at midnight.
Lex Fridman (51:12.620)
So having a cup of coffee at noon,
Lex Fridman (51:14.820)
one could argue is the equivalent
Matt Walker (51:16.220)
of tucking yourself into bed at midnight,
Lex Fridman (51:18.060)
and before you turn the light out,
Matt Walker (51:19.580)
you swig a quarter of a cup of coffee.
Lex Fridman (51:22.180)
But that doesn't still answer your question
Lex Fridman (51:24.300)
as to why are you so immune?
Lex Fridman (51:26.220)
So I'm someone who is actually unfortunately
Matt Walker (51:28.140)
very sensitive to caffeine.
Lex Fridman (51:29.500)
And if I have even two cups of coffee in the morning,
Matt Walker (51:34.980)
I don't sleep as well that night.
Lex Fridman (51:37.260)
And I find it miserable because I love the smell of coffee.
Matt Walker (51:40.660)
I love the routine.
Lex Fridman (51:41.940)
I love the ritual.
Matt Walker (51:43.540)
I think I would love to be invested in it.
Lex Fridman (51:46.220)
It's just terrible for my sleep.
Lex Fridman (51:47.620)
So I switched to decaf.
Lex Fridman (51:49.420)
There is a difference from one individual to the next,
Lex Fridman (51:52.620)
and it's controlled by a set of liver enzymes
Lex Fridman (51:56.660)
called cytochrome P450 enzymes.
Lex Fridman (52:00.740)
And there is a particular gene
Lex Fridman (52:03.020)
that if you have a different sort of version of this gene,
Matt Walker (52:06.660)
it's called CYP1A2.
Lex Fridman (52:11.580)
That gene will determine the speed
Matt Walker (52:14.700)
of the clearance of caffeine from your system.
Lex Fridman (52:18.100)
Some people will have a version of that gene
Matt Walker (52:20.260)
that is very effective and efficient
Lex Fridman (52:23.020)
at clearing that caffeine.
Lex Fridman (52:24.660)
And so their half life could be as short as two hours
Lex Fridman (52:28.460)
rather than five to six hours.
Matt Walker (52:30.900)
Other people, hands up Matt Walker,
Lex Fridman (52:34.100)
have a version of that gene
Matt Walker (52:35.700)
that is not very effective at clearing out the caffeine.
Lex Fridman (52:40.340)
And therefore their half life sort of sensitivity
Matt Walker (52:43.700)
could be somewhere between eight to nine hours.
Lex Fridman (52:48.140)
So we understand that there are individual differences,
Lex Fridman (52:50.740)
but overall, I guess the top line here is drink coffee
Lex Fridman (52:56.580)
and understand that it's not the caffeine,
Matt Walker (52:58.420)
it's the coffee that's the benefit
Lex Fridman (53:00.060)
and the dose makes the poison.
Matt Walker (53:01.300)
Is there some aspect to it that it's like a muscle
Lex Fridman (53:04.860)
in terms of all the combination of letters and numbers
Lex Fridman (53:08.220)
that you just said?
Lex Fridman (53:09.060)
Is there some aspect that if I can improve
Matt Walker (53:13.860)
the quarter life, the half life,
Lex Fridman (53:15.740)
could decrease that number if I just practice?
Matt Walker (53:19.940)
Like I drink a lot of coffee,
Lex Fridman (53:21.380)
so like habit alters how your body's able
Matt Walker (53:25.500)
to get rid of the caffeine.
Lex Fridman (53:27.180)
Not how the body is able to get rid of the caffeine,
Lex Fridman (53:30.180)
but it does alter how sensitive the body is to the caffeine.
Lex Fridman (53:34.540)
And it's not at the level of the enzyme
Matt Walker (53:36.700)
degrading the caffeine.
Lex Fridman (53:38.780)
It's at the level of the receptors
Matt Walker (53:41.460)
that caffeine will act upon.
Lex Fridman (53:44.100)
Now it turns out that those are called adenosine receptors
Lex Fridman (53:46.940)
and maybe we can speak about what adenosine is
Lex Fridman (53:49.100)
and sleep pressure and all of that good stuff.
Lex Fridman (53:51.180)
But as you start to drink more and more coffee,
Lex Fridman (53:56.300)
the body tries to fight back
Lex Fridman (53:58.940)
and it happens with many different drugs by the way,
Lex Fridman (54:01.100)
and it's called tolerance.
Lex Fridman (54:03.100)
And so one of the ways that your body becomes tolerant
Lex Fridman (54:06.660)
to a drug is that the receptors that the drug is binding to,
Matt Walker (54:10.100)
these sort of welcome sites, these sort of picture myths,
Lex Fridman (54:13.900)
as it were, that receive the drug,
Matt Walker (54:16.300)
those start to get taken away from the surface of the cell
Lex Fridman (54:21.620)
and it's what we call receptor internalization.
Lex Fridman (54:25.100)
So the cell starts to think, gee whiz,
Lex Fridman (54:28.260)
there's a lot of stimulation going on, this is too much.
Lex Fridman (54:31.420)
So I'm just going to, when normally I would coat my cell
Lex Fridman (54:35.580)
with let's just say five of these receptors
Matt Walker (54:38.780)
for argument's sake,
Lex Fridman (54:40.620)
things are going a little bit too ballistic right now.
Matt Walker (54:43.260)
I'm going to take away at least two of those receptors
Lex Fridman (54:46.100)
and downscale it to just having three of those.
Lex Fridman (54:49.100)
And now you need two cups of coffee to get the same effect
Lex Fridman (54:52.860)
that one cup of coffee got you before.
Lex Fridman (54:55.540)
And that's why then when you go cold turkey on coffee,
Lex Fridman (55:01.020)
all of a sudden the system has equilibrated itself
Matt Walker (55:05.380)
to expecting X amount of stimulation
Lex Fridman (55:08.540)
and now all of that stimulation is gone.
Lex Fridman (55:10.140)
So it's now got too few receptors
Lex Fridman (55:12.940)
and you have a caffeine withdrawal syndrome.
Lex Fridman (55:15.660)
And that's why, for example, with drugs of abuse,
Lex Fridman (55:18.500)
things like heroin, when people go into abstinence,
Matt Walker (55:23.700)
as they're sort of moving into their addiction,
Lex Fridman (55:26.700)
they will build up a progressive tolerance to that drug.
Lex Fridman (55:30.620)
So they need to take more of it to get the same high.
Lex Fridman (55:34.140)
But then if they go cold turkey for some period of time,
Matt Walker (55:38.140)
the system goes back to being more sensitive again.
Lex Fridman (55:40.620)
It starts to repopulate the surface of the cell
Matt Walker (55:43.380)
with these receptors.
Lex Fridman (55:44.660)
But now when they reuse and they fall off the wagon,
Matt Walker (55:47.660)
if they go back to the same dose
Lex Fridman (55:49.420)
that they were using before 10 weeks ago
Matt Walker (55:53.060)
or three months ago, that dose can kill them.
Lex Fridman (55:56.500)
They can have an overdose.
Matt Walker (55:58.140)
Even though they were using the same amount
Lex Fridman (56:00.300)
at those two different times,
Matt Walker (56:02.260)
the difference is that it's not the dose of the drug,
Lex Fridman (56:05.780)
it's the sensitivity of the system.
Lex Fridman (56:08.140)
And that's the same thing that we see with caffeine.
Lex Fridman (56:10.980)
In terms of training the muscle, as it were,
Matt Walker (56:13.780)
the system becomes less sensitive, can calibrate.
Lex Fridman (56:17.620)
Is there a time, the number of hours before bed,
Matt Walker (56:22.900)
that's a safe bet to most people to recommend
Lex Fridman (56:27.500)
you shouldn't drink caffeine this many hours?
Matt Walker (56:31.220)
Like, is there an average half life
Lex Fridman (56:33.420)
that you should be aiming at?
Matt Walker (56:35.380)
Or is this advice kind of impossible
Lex Fridman (56:38.060)
because there's so much variability?
Matt Walker (56:39.580)
There is huge variability.
Lex Fridman (56:41.260)
And I think everyone themselves to a degree knows it,
Matt Walker (56:45.300)
although I'll put a caveat on that too
Lex Fridman (56:47.980)
because it's a slightly dangerous point.
Lex Fridman (56:50.420)
So the recommendation for the average adult
Lex Fridman (56:53.180)
and who, where is the average adult in society?
Matt Walker (56:55.660)
There is no such thing.
Lex Fridman (56:56.540)
But for the average adult,
Matt Walker (56:58.460)
it would be probably cutting yourself off maybe 10 hours
Lex Fridman (57:02.540)
before.
Lex Fridman (57:03.380)
So assuming a normative bedtime in society,
Lex Fridman (57:06.260)
I would say try to stop drinking caffeine before 2 p.m.
Lex Fridman (57:10.900)
and just keep an eye out.
Lex Fridman (57:13.140)
And if you're struggling with sleep,
Matt Walker (57:14.500)
dial down the caffeine and see if it makes a difference.
Lex Fridman (57:18.060)
Can I ask you about sleep and learning?
Lex Fridman (57:22.500)
So how does sleep affect learning?
Lex Fridman (57:25.420)
Sleep before learning, sleep after learning,
Matt Walker (57:30.420)
which are both fascinating kind of dynamics
Lex Fridman (57:33.100)
of the mind's interaction with this extra conscious state.
Matt Walker (57:37.940)
Yeah, sleep is profoundly and very intimately related
Lex Fridman (57:42.260)
to your memory systems and your informational systems.
Matt Walker (57:46.620)
The first is you just mentioned is that
Lex Fridman (57:48.660)
sleep before learning will essentially prepare your brain
Matt Walker (57:53.380)
almost like a dry sponge ready to sort of,
Lex Fridman (57:56.820)
you know, initially soak up new information.
Matt Walker (57:59.140)
In other words, you need sleep before learning
Lex Fridman (58:01.180)
to effectively imprint information into the brain
Matt Walker (58:04.900)
to lay down fresh memory traces.
Lex Fridman (58:07.900)
And without sleep, the memory circuits of the brain,
Lex Fridman (58:10.980)
and we know we've studied these memory circuits,
Lex Fridman (58:13.940)
will, you know, they essentially become waterlogged
Matt Walker (58:16.980)
as it were for the sponge analogy,
Lex Fridman (58:18.460)
and you can't absorb the information as effectively.
Lex Fridman (58:23.900)
So you need sleep before learning,
Lex Fridman (58:26.300)
but you also need sleep unfortunately after learning too,
Matt Walker (58:30.140)
to then take those freshly minted memories
Lex Fridman (58:33.580)
and effectively hit the save button on them,
Lex Fridman (58:36.180)
but it's nowhere near as quick as a digital system.
Lex Fridman (58:38.700)
It takes hours because it's a physical biological change
Matt Walker (58:42.100)
that happens at the level of brain cells.
Lex Fridman (58:45.020)
But sleep after learning will cement and solidify
Matt Walker (58:49.500)
that new memory into the neural architecture of the brain,
Lex Fridman (58:53.300)
therefore making it less likely to be forgotten.
Matt Walker (58:56.900)
So, you know, I often think of sleep in that way as,
Lex Fridman (59:01.300)
it's almost sort of future proofing information.
Lex Fridman (59:04.580)
In what way?
Lex Fridman (59:06.940)
Well, it means that it gives it a higher degree of assurance
Matt Walker (59:11.940)
to be remembered in the future
Lex Fridman (59:15.060)
rather than go through the sort of degradation
Matt Walker (59:19.380)
that we think of as forgetting.
Lex Fridman (59:22.180)
So the brain has in some ways by default,
Matt Walker (59:26.380)
you know, there is forget,
Lex Fridman (59:28.140)
and actually I would love to,
Matt Walker (59:29.900)
I was going to say sleep is relevant for memory
Lex Fridman (59:31.900)
in three different ways,
Lex Fridman (59:33.220)
but I'm going to amend that
Lex Fridman (59:34.700)
and say there's four different ways,
Matt Walker (59:36.820)
which is learning, maintaining, memorizing,
Lex Fridman (59:42.940)
abstraction, assimilation, association, then forgetting,
Matt Walker (59:47.740)
which the last one sounds oxymoronic
Lex Fridman (59:50.460)
based on the former three, but I'll see if I can explain.
Lex Fridman (59:53.460)
So sleep after learning then sort of, you know,
Lex Fridman (59:57.420)
sets that information like amber in solidification.
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