Dr. Matt Walker: Using Sleep to Improve Learning, Creativity & Memory | Huberman Lab Guest Series

[Music]

welcome to the hubman lab guest Series

where I and an expert guest discuss

science and science-based tools for

everyday

life I'm Andrew huberman and I'm a

professor of neurobiology and

Opthalmology at Stanford School of

Medicine today's episode marks the

fourth in our sixth episode series all

about sleep with expert guest Dr Matthew

Walker during today's episode we discuss

sleep and learning as well as the impact

of sleep and the specific stages of

sleep on creativity and memory we talk

about when and how long to sleep

relative to different bouts of learning

as well as the role of naps in

consolidating information that you are

trying to learn we discuss the science

and Protocols of sleep as it relates to

both cognitive learning and motor

learning and the mechanism by which

sleep encodes memories as with the

previous episodes in this series today's

episode includes information about the

biology of sleep as well as practical

tools that is protocols in which you can

use sleep to improve your learning

memory and creativity before we begin

I'd like to emphasize that this podcast

is separate from my teaching and

research roles at Stanford it is however

part of my desire and effort to bring

zero cost to Consumer information about

science and science related tools to the

general public in keeping with that

theme I'd like to thank the sponsors of

today's podcast our first sponsor is

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huberman today's episode is also brought

To Us by waking up the waking up app is

a meditation app that offers hundreds of

guided meditations mindfulness trainings

yoga need your sessions and more I

started meditating over 30 years ago at

that time there wasn't very much science

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but by now we know that there's a lot of

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trial again that's waking up.com

huberman and now for my conversation

with Dr Matthew Walker Dr Walker Dr

hubman welcome back we have covered a

lot of material first episode of this

series you gave us an overview of sleep

and some actionable items about sleep

then in the second episode you gave us

far more actionable items of how to

think about one sleep in a way that

leads to very concrete decisions about

controlling light temperature when to

sleep and then some really

in-depth Advanced tools or protocols as

we call them and then in the third

episode we talked about caffeine and

napping and some other things that

people can do to really supercharg their

alertness through sleep augmentation in

the daytime and today we're going to

talk about sleep learning in memory and

a topic that I know everybody is very

interested in creativity indeed

resplendant pleasure to be back on the

show thank you for having me yeah

absolutely so I think nowadays most

people understand that there's some

relationship between sleep and learning

but I think it would still be a good

idea for us to zoom out a bit and and

establish what that relationship is you

know I I think most people are familiar

with being exposed to some new material

cognitive material physical uh skill

material and not being able to learn it

right away but then having a few days in

between and then all of a sudden voila

yeah there's uh the skill has been

embedded it seems but not obvious in

that scenario is that sleep is perhaps

the pivotal event that allowed the

learning process to take place so how do

you think about sleep as it relates to

learning and memory I think I've

conceptualized it in three different

stages or three different buckets of a

benefit the first is that we need sleep

before learning to prepare your brain to

initially imprint and lay those memory

traces down but then you need to sleep

after learning to take those sort of

freshly minted memories and then save

them and cement them into the brain so

that you don't lose them the third

domain is that sleep will then take

those new memories that you've been

learning and it will start to collide

them with all of this back catalog of

information that you've already got

stored in your brain and it updates the

iOS of your informational systems so

that then you come back the next day and

you have a better abled ability to

understand how the world Works in other

words the difference between knowledge

which is learning the facts and wisdom

which is knowing what it all means when

you put it together that's the third

category and why is that beneficial

because it provides you with creative

insights and so we will will perhaps

just double click on each of those three

and I can I can expand them because the

data behind them is utterly fascinating

as you said I think many people

subjectively have a sense that sleep

helps me with my memory in some way but

in what way and for people I think one

of the things that you do here is not

just protocols but you help explain the

conceptual understanding or the

conceptual mechanisms underlying the

reasons for all of the these protocols

and I would love to dive into detail

yeah so let's do that let's talk about

this business of sleeping before

learning you know

essentially establishing a millu within

the brain that is optimal for learning

what what is that about and

neurochemically at the level of circuits

and um what is the evidence that

providing some I don't know additional

sleep or just adequate sleep prior to

the exposure to the new material can be

beneficial yeah I that word that optimal

millu and it beautifully describes what

we found we started off asking a very

simple question at my sleep center is

pulling the allnighter a wise

idea so we took a group of perfectly

healthy smart individuals and we

assigned them to one of two experimental

groups a sleep group and a sleep

deprivation

group and both of those groups went

through those two different protocols

and then the next next day after sleep

or after no sleep we put them inside of

a brain scanner and we had them try and

learn a whole list of new facts as we

were taking snapshots of brain activity

and then we tested them to see how

effective that learning had been when we

looked at the group that had had a full

night of sleep they had incredibly

efficient learning capacity so in other

words they had learned and imprinted

that information initially very well

well when we looked at the sleep

deprivation group not so much in fact

there was a 40% deficit in the ability

of the brain to make new memories

without sleep and we've used lots of

different types we've replicated that

now we've had visual information we've

had textbook like information and the

range is somewhere between 20 to

40% I find that by the way striking and

we can come back to this based on what

we are seeing in our Educational Systems

right now there is this parcity of sleep

because of this model of early school

start times and I'll explain exactly

what's happened there and what we've

been doing to try to change that but

coming back to those two groups the

Sleep group and the sleep deprivation

group what was going on as you said

inside of the brain that would help us

understand why they couldn't learn or at

least couldn't learn

effectively and the structure that we

focused on is one you've spoken about

before called the

hippocampus and you have one on the left

side and the right side of your brain it

looks like a long cigar that runs down

the left and right side of your brain

and people listening can think of the

hippocampus almost like the

informational inbox of your brain it's

very good at receiving new memory files

and then holding on to them and when we

looked at that structure and its

activity during learning in the Sleep

group they had wonderful powerful

activation of the hippocampus as if it

was gobbling up all of that new

information into the inbox when we

looked at the sleep deprivation group

however we couldn't find any significant

signal

whatsoever so it was almost as though

sleep deprivation had shut down the

memory inbox and any new incoming files

they were just being bounced you

couldn't effectively commit new

experiences to

memory and then subsequent stes that

were not done by us but uh looking at

animal models they were looking at how

able the synapses are in that memory

structure the hippocampus how capable

those synapses are for building new

connections and the synapses are just

those connections between neurons and we

think that part of the way that we make

memories is by strengthening the

connection in the memory circuit itself

and what they found was that when they

restricted the sleep of these rats or

the mice that part of the brain became

very stubborn it just wouldn't form

those new synaptic connections and

something that we call synaptic

plasticity so we started to understand

this was the bad that happened when you

take sleep away but let's come back to

that control group that I said got a

full night of sleep exactly what is it

about sleep when you do get it that

seems to support and promote your

learning

ability so we decided just do another

different study instead of manipulating

sleep by dialing it down we instead

tried to dial it up by way of a daytime

nap and again we took two groups and we

had them initially learn again a huge

amount of factual information they

learned it over and over and over again

and then we brought them back 6 hours

later at 6pm and now we had them learn a

whole new set of information and after

each one of of those fresh novel

learning sessions we tested them to see

how effective that learning had been

again one of those groups spent that 6

hours of time awake doing just relaxing

activities the other group was able to

obtain a 90-minute nap and we Ed that

90-minute nap to allow them to go

through a full sort of average cycle to

get some non-rem and to get some

REM what was interesting is that when we

tested the group that remained awake

later that fall following day the

learning capacity had

declined but in the nap group it seemed

to restore the brain's capacity to learn

and you didn't get that decline in

memory in fact if anything you got a

little boost and the difference between

those two was about 20% so it's quite a

nice benefit yeah not trivial not

trivial at all and then we said okay

well if sleep is doing something what is

it about that sleep so we unpacked the

physiology of sleep and the different

stages of sleep that we discussed in the

first episode and what we found was that

it was the nonrapid eye movement sleep

or the non-rm sleep and particularly

those sleep spindles those short bursts

of electrical activity that we have

discussed before that seemed to predict

how restored and refreshed your learning

ability

was and the best way that I've been

thinking about this in terms of sleep

storing or refreshing your encoding

ability and it's a crash analogy and I

don't mean to make a direct brain to

computer analogy but think of that

hippocampus almost like a USB stick

that's very good during the day at going

around and grabbing new files but it has

a limited storage

capacity and what sleep was doing seemed

to be shifting those memories from the

USB stick of your hippocampus over up to

the cortex which you can think of almost

like your hard drive a much bigger

storage capacity and by way of doing

that when you woke up after the nap or

after a full night of sleep you had this

cleared out USB stick so what could you

do you could go around and start

acquiring all these new files

again so that started to teach us a

little bit about why sleep before

learning is critical but also

mechanistically how sleep is doing this

remarkable work of memory restoration

we then wanted to say well can we

translate this out into the real world

and I think there are two regions that

we've moved this workout into one is

education one is is medicine and

Alzheimer's disease but the education

piece was very

interesting in the United States I think

the last time I checked the average

school start time is somewhere around

7:30 745 sounds about right and if you

think about that for 7:30 school start

time

school buses will begin leaving around

5:30 5:45 in the morning mhm that means

that some kids are having to wake up at

5:00 a.m. maybe even earlier this is

lunacy when you think about it there's a

great study in edner I hope I'm

pronouncing that correct edner which is

a small suburb or it sits in a small

suburb outside of Minneapolis in

Minnesota and they shifted their school

start times from 7:25 5 to 8:30 in the

morning and then they wanted to ask what

is the consequence of that on the

academic performance of their students

and the metric that they used in these

teenagers that they were focusing on was

something called the SAT score which is

a score I had to learn when I first came

to the United States is a critical

assessment test that will largely

determine which university you go to and

they did an analysis which was clever

they focused on the top 10% performing

students which you could argue those are

the ones that are closest to the ceiling

performance and the hardest to expect

any benefit from sleep so in the year

before they made the time change the

average score of those top 10%

performing students was

1,288 which turns out to be a pretty

good SAT score the following year after

they made the time change the average

score for that top 10%

was

1,500 that difference is non-trivial and

it will change exactly where those

individuals will go to university in

terms of the tier of the university and

likely change the trajectory of their

lives as a consequence now some people

have argued that data you know in terms

of its source and its reliability may

not have necessarily been accurate but

now we've got very consistent data when

you start school times later academic

grades improve psychological and

psychiatric problems decrease truancy

rates

decrease but something else happened in

that story of later school start times

that we didn't expect which was that the

life expectancy of students increased

and you think well hang on a second how

do you determine that the number one

cause of death in teenagers 16 to 18 is

actually not suicide turns out to be

second it's road traffic

accidents and here sleep matters

enormously there was another great

example from tetan County in Wyoming and

they shifted their school start times

from I think it was 7:35 in the morning

to

8:55 and the only thing more remarkable

than the extra 1 hour of sleep those

kids reported getting was the drop in

car accidents that following year there

was a 70% reduction in car crashes in

that age range of 16 to 18 what time are

they getting out of school well they

will probably be ejected out of school

that's another interesting part by the

way maybe around

4:30 and people have said well look all

of this idea of later school start times

it means that it's going to cost us more

cuz you've got to change the school bus

system and they've argued push back

against that and I would say

probably two things first I know it's

difficult and I'm not saying it's an

easy problem to do it's a complex

problem and I'm sympathetic to that but

I I think we've put people on the moon

and so I suspect that we can also solve

the problem of early school start

times the the other component of that

is what are we doing as Educators if our

goal as educated is true truly to

educate and not risk lives in the

process then we are failing our children

in a most spectacular manner with this

incessant model of early school start

times and if you look at the data it's

very clear when sleep is abundant Minds

flourish and when it's not they

don't and so that's the reason why

myself and a whole group of sleep

scientists we started to try to create a

movement for later school start times

and we got this bill passed firstly in

California we got it on the governor's

desk at the time who was governor uh

Brown and unfortunately he didn't sign

it into law then when the organization

changed and Governor nusum came in as

governor of California we got the bill

back on the on his desk and he did sign

it and then uh the next state to go was

New York they started to put in

legislation for recommendations for

later school start times I think Florida

is about to fall as well in that regard

so there's gradual movement happening

but it's hard fought and it's it's

problematic I still think that it's it's

impossible to deny that data I mean it

was an interesting thing I remember when

I was a professor back at Harvard we

were doing this work on sleep and and

learning and they said and it was sort

of published in these sort of um kindly

I don't know how we did it but in nice

journals and they said okay based on the

media attraction would you write an

editorial for the Harvard newspaper

which was called the Harvard Crimson I

said I'd love to so at first I thought

I'm just going to write a straight piece

about sleep and memory and why it's

important then I realized no there's a

better opportunity because teaching

there and you know this as well as I do

there is this bizarre system where we

teach for an entire semester and then we

endload the semester full of exam in

this stressful 2 we period and what do

you think is going to happen they're not

going to sleep especially at a time when

they're trying to cram information so

especially in college where you don't

actually have the material four weeks

before so there's not really the option

to learn it in advance no everything's

about University to me was about getting

a bunch of information and needing to

incorporate it very quickly and then

move to the next item right next item

next item and then all of a sudden

there's this cataclysmic moment at the

end of the semester and you are supposed

to regurgitate this by cramming

everything into your brain in this

Sleepless twoe period so rather than

saying look the students need to change

their behavior they need to understand

this is problem it's not their fault I

said it's us as Educators and

administrators we have created a system

that forces them to undergo deliberate

sleep deprivation and we are educating

them amnesic quite

literally so I put this uh editorial out

it received a um a rather Baltic if not

Arctic response and um that was the last

editorial I was ever invited to to write

for the newspaper but you know you've

got to say your piece well so but I'm

curious why there's resistance to

shifting to later School times and to

improving the conditions for learning if

the goal is to learn I mean tradition

dies hard um maybe that's why um I think

there's also the idea certainly in the

medical profession that you know well

when I was doing my training we would

pull all nighters all the time um and so

the idea then is that it's just part of

The self-directed Hazing process that is

getting a degree that you're going to be

doing a lot of allnighters and cramming

and things of that sort is that is that

why you think motivates the the

resistance to change I think so I think

you've hit all the points I think you

know Zeitgeist die one generation at a

time and we see that resistance

certainly there

too I also think that when you come back

to later school start

times they have suggested that there is

this cost when they tally it up but you

made a point which is when did they get

out of school and let's say it's around

4:30 one of the interesting analyses

that was published and we latched on to

this

that is this strange bewitching hour

when kids get out of school but often

their parents are not home to work and

if you look at the Teenage Crime rate

and you look at when those crimes are

committed it's usually in that

bewitching hour after they get out of

school but they don't have a home or

parents yet to go to that filled but by

pushing school start times later they

get out later they go home

and if you were to even half that debt

that those crimes cause you would easily

pay for the education system so it's

very interesting I think that also

notion of well we went through it and

here I am so you can go through it too

is very prevalent in medicine this is

another good

example we and mostly um colleagues at

mine such as Charles Eisler at Harvard

have really done a great job job at

cataloging exactly why we need to

abandon this resident program which has

a fascinating history by the

way which is Young residents should be

working 30-hour shifts often without any

sleep whatsoever and when you look at

that data residents who are working a

30-hour shift are going to be almost 460

more likely to make diagnostic errors in

the Intensive Care Unit if you have a

surgeon and you're getting elective

surgery who's had less than 6 hours of

sleep in the previous 24 they are almost

70% more likely to cause a surgical

error which could result in non-trivial

consequences and then the irony is that

when young residents after a 30-hour

shift get back into their car at the end

of the shift and drive home there is

168% increased risk that they get into a

car accident and then end up back in the

ER from from where they just came but

now as a patient rather than a physician

and you think what are we doing I

Charles E I think has

described they provided this evidence to

the council and at first they just I

think the idea was look our minds are

made up don't confuse me with the

data and you appeal on the empathetic

basis but it wasn't well received so

then if you go back and you say no I'm

going to give you a different argument

if you look at the cost of malpractice

caused by insufficient sleep and if you

get the administrators into the room all

of a sudden the schedules change so then

based on that data there was a policy

that you couldn't work any longer than I

think it was a 16h hour continuous

shift the problem was that they only

said that that was apparent for the

first year residence and not the

remaining years and the question was

well why I said well the data that you

showed us you only collected in firste

Residence as if something magical was

going to happen when you become a

second-year resident and you Dawn this

TEF long coat of immunity against sleep

deprivation well if anything it would

compound to get worse so so it seems to

me that um there's there's like zero

question that getting adequate sleep is

good for learning but and when the

stakes when it's high-risk High

consequences scenarios or even high

consequences scenarios like a

medical situation um just seems like uh

should almost come down to Legal

liability yeah I'd like to take a brief

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huberman so are the

errors of sleep deprivation in these

scenarios both in students and medical

professional are they due to errors in

memory per se I mean so I mean because

you can imagine all sorts of Errors so

with a surgeon they like cut the wrong

thing or they cut too far the margin on

the surgical side is too big Etc but

since we're talking about learning in

memory um and its relationship to sleep

uh is it that people are forgetting what

they did are they forgetting what they

didn't do I mean um or is it a deficit

in motor skills or all of the above it's

all of the above above plus which is

that learning in memory your

recollection of both what you did or

what you need to do or what you should

do based on your training is going to be

compromised because your recall of that

information it turns out is also

compromised but it's also

decision-making too that what we know is

that your frontal lobe is especially

sensitive to a lack of sleep and it's

that frontal lobe that really takes

complex situations to Stills them down

and comes up with the correct output

scenario of decisions that you need to

make

not so much when you're sleep deprived

so how should I establish the

proper neural millu for learning by

sleeping prior should I make sure that I

I mean in an Ideal World I get excellent

night sleep for the you know every day

of my life leading up to about of

learning being Expo and here I'm

referring to about of learning as being

exposed to new material

but life happens um so if I know that

tomorrow I'm going to take a class in

something or I'm going to need to

perform a skill that it's pretty nent

skill for me I only learned it recently

what should I do the night

before I would say think about what you

can get in terms of your sleep under

current conditions and understand that

that

is staying awake and foregoing

sleep is not the right equation that you

may think in other words think of sleep

that night as an investment in tomorrow

rather than a cost opportunity of now or

today that would be the message I think

for learning in memory some people will

say logically and rationally well but if

I stay awake I can at least be learning

and going over that material for many

more hours so doesn't that compensate

for me going to bed let's say I haven't

learned it well enough well surely I

should just you know say I I should just

focus and stay awake CU at least then I

can just go over the material Time and

Time and Time Again doesn't that offset

the the deficit and to a degree it does

we did that study but what was really

interesting is that the next day were

you able to at least learn and recall

some of that information to a degree yes

you were and the more that you kept

going over it the better you performed

even when you were not getting

sufficient sleep but then we did

something interesting we then brought

them back we haven't published this this

St I should do we brought them back a

month later and then we tested them

again and what you find is that the

group that slept was far better able to

have retained and remember that

information whereas the group that did

not sleep as much they performed much

more similar to the group that got a

full night of sleep the next day but

when you test them a month later almost

none of that material is residing in

their brain anymore got it so this is

the cramming effect that's right right

and and if one knows this from teaching

university courses um or if they've

crammed that you can learn a bunch of

material but then you regurgitate it for

the exam and then it's gone yeah so so

it's almost like a it just never passes

from short-term to long-term memory

essentially that's correct okay and that

seems to be in some ways that's a

beautiful description of then what

happens next in the Sleep process it's

not just about sleep before learning you

then have to sleep after learning to do

exactly what you just described

so I have an class in the morning or I'm

going to learn something new the next

day afternoon my goal presumably should

be to maximize the amount of sleep I

get and to be on the same sleep schedule

so this gets back to qqr that was

presented in the first episode quantity

quality regularity and timing I people

should refer to that um nothing wrong

with your memory by the way well I don't

know about that but um the um the qqt

formula was was described in the first

episode um let's come up with a what I

think is a fairly common scenario so I

like to go to bed early between 800 and

900 p.m. I discovered this recently

thanks to conversations with you this is

clearly what works best for me I kind of

always inted it but I um it clearly is

what works best if I go to bed at 10:00

I probably want to wake up sometime

around I don't know 6:00 a.m. or or 6:30

and um if I go to bed any later than

10:30 I start running into problems I

don't feel good the next day even if I

get sufficient hours of sleep so this is

the importance of regularity and timing

keeping things more or less locked to

that 8:30 to 9:30 to bedtime for me 4:30

to 5:30 wake up time that's me just by

way of example in an Ideal World

therefore I would stick to that schedule

wake up the next day and go do my

learning or my performance of something

that IID learned someone else might have

the chronotype we're going to bed at

11:00 p.m. and waking up at 7:30 a.m. is

their preferred schedule

however often because of travel because

of courses because of Life

circumstances the night before something

critical that we need to learn or to

perform some critical task physical or

cognitive the Sleep the night before is

disrupted in some way either by virtue

of timing or quantity and then of course

by extension regularity so is there

anything that we can do heading into a

bout of learning meaning the night

preceding that bout of learning that can

kind of um provide a buffer or or set us

up for the best possible learning

scenario if we're not able to stick to

our perfect

schedule I think there may be two things

there's been a little bit of work that's

been done um to suggest that caffeine

may actually enhance the hippocampus

this memory encoding structure and boost

its ability to encode now what they

haven't yet done is the study where you

sleep deprive someone then you give them

caffeine the next day and then you have

them try to learn and ask can caffeine

by way of its effect on the

hippocampus rescue and restore what

would otherwise be an encoding deficit

now that is entirely possible and I

think it's a fascinating question by how

much we don't know but if it doesn't

it's equally likely that the hippocampus

by way of being sleep deprived is not

receptive to the benefit of caffeine

under conditions of sleep deprivation

and I told you in the rat studies when

those rats were deprived the hippocampus

once again became stubborn in its

ability to form new synapses and it may

be that it's equally stubborn to receive

the normal benefit of caffeine when you

are sleep rested but I would love to do

that study the second is to then say

well if I have the choice of when I'm

going to be learning during the day

let's say that you've had a bad night of

sleep or you just had a short night of

sleep non-negotiable couldn't do

anything about it and the next day I've

got to cram in some information I would

say think about your chronotype and

think about when you are at your best

operating temperature so your scenario

let's say going to bed at 9: waking up

at

4:35 your Peak is probably going to be

maybe 10 11:00 in the morning where your

biology and your Cadian rhythm is on its

almost Crescendo Peak at that point we

know for Cadian influences on learning

and this is independent of sleep

influences on learning that's where

things are better now for me you

actually described me which is I'm a

kind of an 11 to 730 type person for me

it's probably going to be much closer to

about midday or 1: p.m. where I feel at

my operating Peak both for physical

performance and also mental performance

so if you've got the choice and you are

underslept there's nothing you can do

about the sleep that you've lost the

night before but at least recognize that

your Cadian rhythm is going to come to

your rescue and help offset that as long

as you time you're learning to that

known peak of your Cadian Rhythm does

that help a little bit yes that that

makes good sense so the idea gets us

back to something you described in

previous episodes which is that you have

this sleep pressure due to the buildup

of the molecule adenosine which the

longer we are awake the more adenosine

in our nervous system which makes us

sleepy but separate from that there's

this circadian circadia about 24-hour

Rhythm right

um that causes fairly dramatic shifts in

wakeful fullness and sleepiness

independent of the adenosine signal now

sometimes the two signals overlap so

that late in the evening for instance we

have a lot of adenosine we've been up

all day and our circadian rhythm is such

that our alertness is starting to

diminish so they're aligned and in the

early part of the day assuming

everything is normal the adenosine

levels are low because we slept well the

night before and our circadian rhythm is

on the upswing so to speak um and we are

alert so if I understand correctly the

goal is to of course Maxim the quality

quantity regularity and timing of sleep

qqr but that in the absence of the

ability to really anchor any one of

those things to 10 out of 10 you know A+

performance if one knows that okay

typically around you know between 10:00

a.m. and noon is when I'm at my sharpest

that would be the time to be exposed to

new material or ideally take an exam if

one can control that sort of thing and

then perhaps in the afternoon there's

another opportunity be uh after the

postp perenial dip that's right but

before the post perenial dip sometime

between 1 and 4 pm usually lasting about

an hour to 90 minutes this is a dip

natural dip in energy but then after

that is another opportunity to learn um

sure there'll be a lot of adenosine in

one system because you've been a long

time um but the Circadian system is on

its sort of uh upswing again before the

down swing that occurs in the evening is

that right right opportunities um and by

the way it's strange you were to ask if

you look at the Cadian Rhythm right

before sort of bedtime there is this

sort of strange little blip this peak um

that Folks at um back at Harvard have

have discovered and you think well why

would my Cadian system which needs to

really ratchet down for us to get to

sleep well why would it have this little

Jag

upwards in the evening hours right

before we need to sleep and it then

drops precipitously right makes no sense

until you think about Evolution because

after foraging for food during the day

what you need is this final spurt to get

you home safely to your nest or to your

home yeah to batten down the hatches

exactly so there is this beautiful

little built-in Cadian upswing to say

okay I know you're returning to home

this is probably a time when there's

some maybe Potential Threat to you I'm

going to just boost your alertness very

quickly so you travel home safely good

to go great and now I stopped my

downswing I think this is a really

important thing for people to know about

um I'm familiar with the data uh

although just in top Contour but the

idea here as I understand it is that

many people will feel like okay around

6:00 p.m. 6:30 they're getting sleepy

7:30 8:00 p.m. and then they want to get

to bed at 10:30 and suddenly for them

based on their chronotype around 9:00

p.m. they're like Wide Awake second wind

right the second wind and they're like

oh no I need to sleep tonight um now

maybe it's the case that they a they

would be better off going to bed far

earlier and waking up earlier the next

morning but in many cases it's just that

transient 45 to 6 you know 70 minute

window of increased uh alertness this

kind of um uptick in the in the

Circadian system so to there's two shell

pass and then also just set yourself up

for success and we discuss a little bit

about the methods of really ratcheting

things down dimming Down the Lights

having a tiet alarm these types of

things will just gradually back you off

and after that second wind comes give

you the greatest ability to decline

physiologically which then permits this

beautiful thing called Sleep to come in

its place well speaking of sleep post

learning um what is the role of sleep

that follows about of learning and here

again we want to Define learning as the

exposure to novel information that one

is trying to encode either cognitive

information motor information or or

combination of the two um and I say that

because learning AKA neuroplasticity has

many different stages it's a process not

an event but um so let's say that uh

earlier in the day I took a dance class

Lord knows I need one or um you and both

or a musical lesson or was exposed to

some interesting information who knows

maybe on a podcast and I was you know

trying to engage in that information and

and pay attention and then that night I

I plan to sleep um or perhaps one could

take a nap after this bout of

learning how close to the learning

episode about as I'm calling it does the

sleep have to arrive in order for sleep

to maximize the amount of learning that

occurs is very good question which

is what would happen if I were to be

learning information and I'm listening

to um this odd British gentleman should

I then immediately dive into bed so that

I maximize the retention of that

information and the answer is no don't

worry and I'll come back to why not to

worry um but to your point not only do

you need sleep before learning as we've

been discussing but there is something

unique and equally necessary of and

causally necessary I should say for

sleep after learning but it does

something different sleep before

learning gets your brain ready to lay

down those new memory traces after

you've imprinted them into the brain

sleep after learning then takes those

freshly minted memories and then it

strengthens them it all essentially it's

almost like sleep will hit the save

button on those new memories so that you

don't forget so in other words sleep is

future proofing that information within

your brain so that you don't

forget and then the question and we've

been able to and we and many others have

replicated this in fact it's nothing new

if you look at the literature on this

sleep after learning um

gig it goes back as best we can tell to

1929 although I'll argue with that in a

second but two researchers Jenkins and

dback did a landmark study they had

participants learn a whole bunch of

nonsense syllables and they had them

learn them over and over and over again

and gradually they got better and then

they started to test them across an 8

hour period they tested them 2 hours

later 4 hours later 6 hours later and 8

hours later the only difference is that

in one of those testing sessions that 2

hours 4 hours 6 hours 8 hours was a

cross awaking day in the other they had

them learn that information to near

Perfection before sleep just as they did

in the waking group but now they woke

them up after 2 hours and tested them

after 4 hours and tested them after 6

hours and then again when they woke up

in the morning 8 hours later and what

they found is that in those people who

stayed awake after learning there was

essentially just catastrophic forgetting

the amount of information 2 hours 4

hours 6 hours 8 hours later just

declined dramatically

but when they repeated that in the same

individuals after learning things to the

same degree 2 hours 4 hours later memory

was starting to decline but after about

two and a half three hours of being

asleep all of a sudden sleep had fixated

those memories almost like um like an

animal that's been trapped in Amber and

set in Amber like a fossil and then

those memories just would not Decay any

further and you retained them what was

stunning about that study is it has been

replicated time and time again that's

not the surprising part the surprising

part is that in that study they tested a

vast number of subjects in fact a sum

tootal of two

participants but what's stunning is that

that finding has gone and been

replicated time and time again so that

demonstrated to us that there's

something special about sleep that is

concretizing almost literally like

taking things and setting it in

concrete and then the question became

again mechanistically how how is it and

it's important to understand mechanism

because it has ramifications for

diseases and Medicine how is sleep doing

this fantastic saving of memories and we

now have at least two non-mutually

exclusive mechanisms so in other words

both seem to occur the first is what we

call memory translocation

sleep and particularly what we found for

fact-based memories and I should note by

the way that this story of sleep after

learning is a two-part or it runs in two

different narratives one is sleep after

learning for fact-based memory what we

describe as declarative memory and

you've uh done a fantastic uh previous

episode on working memory and describe

all of these different types of memory

so one story line has been sleep after

learning for fact-based memory but the

other which is equally interesting is

sleep for non declarative or procedural

skill memory in other words what we

think of as motor memory but I'll come

back to motor memory in a

second what we then found for this sleep

and textbook like memory is that there

are two mechanisms the first

translocation and here what we found is

that it's deep nonrem sleep for

fact-based memories and it's those big

slow powerful brain waves that we spoke

about in the first episode combined with

those sleep spindles that ride on top of

them almost like a surfer on a huge

amplitude

wave and it's the combination of those

two brain waves that acts like a file

transfer mechanism and it moves and

shifts memories from a short-term

vulnerable Reservoir the hippocampus to

the more permanent long-term storage

site the cortex in the brain and

therefore protect protecting them and

making them

safe so that's one mechanism is the the

shifting of memories around the brain

and through different storage sites from

short term to long

term the second I think is perhaps even

more fascinating it's called memory

replay and this was discovered back in

the probably 1990s Bruce mcnorton um at

the University of Arizona working with a

young Matt Wilson who not uh Matt Walker

he's Matt Wilson at MIT now

they were looking at rats and they were

looking at how rats learn a maze and

they had these electrodes in these

hippocampal brain regions um these

memory related regions that we've been

discussing and they were listening to

the individual firing patterns of those

memory cells in the hippocampus as they

were running around the Maze and sure

enough as they ran around the maze

statistically you would build up what

looked like the signature pattern of

learning so think about those neurons

that they each had a special tone to

them and as the rat is running around

the maze you can hear the signature of

learning and just me it over and over

again but then they did something clever

when the rats went to sleep after

learning they kept

listening what did they hear they didn't

just hear noise they heard that same

memory signature replayed

however it wasn't replayed at the same

speed it was replayed somewhere between

10 to 20 times faster so now all of a

sudden instead of

hearing you

heard just going over and over again and

what we've learned is that this replay

of memories for that type of information

now for rats that's the version

essentially of that spatial navigation

is their version of fact-based memory

and I won't go into detail but yeah cuz

navigating novel environments is

especially important for all species but

rodents to know where they cashed food

where escapes are and things of that

sort yeah perhaps even more so than as

humans that locational memory is

necessary and nowadays there's Google

Maps and Uber and things of that sort

but in the the old days as it were I

recall the the London taxi drivers were

considered the um you know the world

heavyweight champions of of uh memory

and there were some decent brain imag

studies of their hippocamp ey and indeed

they have amazing spatial memory of the

city of London um now that's probably

changed because of Google Maps there

there's no need to rely on on um

internal memory stores when you have no

you still actually there's still a now

you can drive you know these ridea apps

but for London taxi drivers they still

have to go through in some ways it's

almost like a hazing it's called the

knowledge and if you if you are visiting

London you will see these strange guys

who are going around on mopeds and they

just have this huge kind of map in front

of them and they are doing the knowledge

which is that they are learning

exquisitly the entire road map of London

and what they found in those studies was

that the size of the hippocampus this

memory structure related to fact-based

memories and also spatial memories was

significantly larger in cab drivers than

it was in matched controls now you could

say well this is a self- selecting

process

that people who already have large

hippocampi as we would say they're just

going to be the people who can do the

knowledge well and pass as it were but

what they also found was that a

correlation the longer that you've been

doing the knowledge and being a taxi

driver the bigger and bigger your

hippocampus so it's time on task so

coming back to the the the rats in this

spatial learning it's almost as though

sleep after learning is taking that

memory trace and it's like etching into

a glass surface you just go over that

memory circuit over and over again and

you're strengthening that memory

circuit what was also fascinating

however I would I'm telling you that

it's during non-r sleep that you do all

of this memory replay and certainly what

we found is that for textbook memory

it's deep non-rem sleep that's the

important stage of sleep but Matt Wilson

published at MIT an interesting study

looking at REM sleep what happens to the

memory Trace in REM sleep and REM sleep

which we know is associated with

dreaming there the memory replay didn't

slow back down to normal waking speed it

slowed down even further to point five

times relative to waking speed so the

waking speed versus the dreaming speed

in dreaming sort of in REM sleep I

should say because we don't know if rats

dream or not but in REM sleep things had

slowed down by essentially

50% and this comes back to our

conversation in a previous episode that

we had about time and you and I were

discussing how there's this strange

phenomenon where you are woken up by

your alarm and you're in a dream and you

have a snooze button that lasts 5

minutes you hit the snooze button you go

back to sleep and you feel as though

you've been dreaming for I don't know 10

minutes 15 minutes but it's been 5

minutes in the real world but time has

slowed down time has dilated it's almost

like a satina that's stretched out and

all of a sudden we were finding in or

Matt Wilson because we don't do animal

research was finding that this replay

was slowed down by 50% so I always

wonder whether or not there is neuronal

evidence that helps us explain why

dreams seem to pack more

time despite being in real world time a

shorter amount absolutely fascinating

yeah I have to imagine that um rat dream

and dog dream and other animal stream I

mean why wouldn't they um you know if uh

all the components of REM sleep that are

expressed in humans appear in these

animals and vice versa you imagine it

almost has to be the case it does and I

think there is some interesting

supportive evidence that you can argue

there is a sleep disorder that we

understood in humans first called rapid

eye movement disorder or REM sleep

behavioral disorder and in the first

episode we said that one of the

fascinating features of REM sleep which

is when we principally dream is that

your brain and specifically your brain

stem paralyzes your body so that your

mind can dream safely so you're shut

down into this motor paralysis

incarceration rightly

so but what also happens is that as we

get older it seems to be particularly

more so in men than in women but it can

be both both once we get past our 50s

there's a higher likelihood that that

mechanism starts to

degrade and you can start to act out

your dreams now this is not sleepwalking

or sleeptalking that actually comes from

deep non-rm sleep and there what happens

is that there is a trigger an Awakening

either a brain response almost like a

stress response that wakes the brain up

and you're in the deepest stages of

sleep and you are trying to get forced

back up to wakefulness sort of the back

to that analogy of going from the

basement to the to the penthouse and

instead you just get locked into this

mixed state of consciousness of and as a

consequence you start to enact very rot

basic behaviors you'll go over to the

refrigerator open the door close the

door pick up a glass put it to your

mouth put it back down and if you wake

someone up which you shouldn't

necessarily do unless there's there's

harm that and ask them what was going

through your mind just a few minutes

minutes ago they all say nothing and the

reason is because it wasn't coming from

dream sleep it was from deep non-re

sleep I see however there is a very

different condition that sometimes

people will mix up as the very same

thing which is REM sleep behavioral

disorder and there you're acting out

your dreams it can be quite violent some

people have enacted violence on their

partner and woken up and being

absolutely

devastated I bring this up however

because human beings are not the only

species that suffers from REM sleep

Behavioral disorder dogs suffer from

this as well and when you see it and you

can understand it's very clear you have

electrodes on the head they go into this

REM sleep State and all of a sudden they

come out of the paralysis and they start

enacting what very much looks like a

behavior of wakefulness it's quite

complex and at that point you look at

that and you

say okay I'm I'm sorry but that looks

very much like dreaming now we can't of

of course ask dogs a question you know

what was going through your mind you can

ask them but they're not going yeah but

yeah you can ask them but it turns out

that the response is is less than it's

just a look to say give me a treat but

you know in science sometimes if it

looks like a duck talks like a duck

walks like a duck maybe it's a

duck what what about um this phenomenon

which I've experienced before of being

asleep presumably in rapid eye movement

sleep and being completely paralyzed but

then waking up and I'm still in

paralysis but I'm not asleep and um this

was a long time ago uh probably the 10th

grade which for me I was what 15 years

old I'm 48 now and um it was at a party

that I I fell asleep on the couch and I

goodness I I don't believe in underage

drinking but there's a there's a

possibility that I might have been

inebriated I I

was kids parents that you know I I just

I actively dissuade young people from

drinking and many older people from

drinking but yeah I started drinking far

too young um and but I remember I drank

the night before I got drunk the night

before again something I'm not um

suggesting or proud of I woke up and I

was wide awake gosh I remember this so

well and I was paralyzed I could not

move and it was terrifying and then all

of a sudden boom I could jolt myself

awake and I was like oh my goodness and

um it must have been in an invasion of

that atonia that sleep induced paralysis

into the waking state so I can explain

this and you have this is the perfect

prototypical situation when we see this

what you're describing to me is

something that many people listening

will have experienced called REM sleep

paralysis and it's not necessarily a

problem or a sign of a condition that

you need to be worried about although if

it's happening frequently we can think

about that what Norm happens when we

wake up out of REM sleep and REM sleep

as we spoke about in the first episode

dominates the second half of the night

and particularly the last quarter of the

night as you're coming out of REM sleep

and waking up out of REM sleep which you

know you've got a 50/50% chance perhaps

cu the other state that you're in a

stage two light non remm as you're

coming out of REM sleep you're regaining

Consciousness to the external world and

then normally in lock step with that

perfect lock step if not a little before

your brain is realizing this and it's

releasing you from the paralysis and we

all wake up and we don't even think

about it I just wake up and I lean over

I turn off you know the alarm and I get

out of bed everything's fine every now

and again however the waking up and

Consciousness re-engaging occurs however

the brain does not release you from the

REM sleep paralysis so at that point

it's almost like a locked in body

phenomenon and it's very frightening

because because you begin to be aware of

your surroundings but you cannot make

any voluntary movements because I told

you that the voluntary sceletal muscle

system is imper by the atonia the

absence of muscle your involuntary

you're still breathing and all but your

eyelids turn out to be part of

your voluntary muscle set so you can't

lift up your eyelids and then normally

what happens is that it's associated

with a strong sense of often an in Ruder

it seems to be if you're doing it sort

of in bed by yourself at home now your

context was a little different and it

turns out that if you look at these

descriptions of sleep paralysis where

you can't wake up you can't shout out

you can't move you have this sense of

another presence or another being in the

room it adequately explains most if not

all alien abduction stories because when

was the last time you saw a news article

or on the news that someone said okay

today it was very clear that Jimmy in

Wisconsin in the middle of the day was

abducted by aliens and everyone saw it

you know you're at the meeting table and

whoosh what happened that was Jimmy he

just got whisked off by alien doesn't

happen that way it's normally that

you're in bed at night it's the early

morning hours just before you're waking

up these aliens came into the room they

injected something into you they

paralyzed you you couldn't shout you

couldn't move

it's simply REM sleep paralysis now when

do we see that there are ways and not

ways because these are not protocols

that we advise there are circumstances

where the probability of that increases

and I've experienced this too when you

are sleep deprived or you are highly

stressed the likelihood that you will

experience these REM sleep paralysis

events upon Awakening is increased and

for me it was happening when I was um a

a young uh PhD student and I was

studying sleep and then I would be awake

all night because I'd be monitoring the

patients and looking at their sleep the

irony of sleep studies exactly that you

have to deprive yourself of the very

thing that you are trying to study and

is which by the way gives you some

amazing insights for experiments that

I've had as a consequence not that I

would advise that as the way and we'll

come on to why that's not wise when we

speak about creativity but we were um

doing these studies and then I would go

home and then I would take a short

period of sleep maybe just 2 and 1 half

hours of

sleep and then I would wake up I didn't

want to cuz I was ready to go deep into

sleep but I would wake up and then I

would force myself to be awake

throughout the day and try to get to bed

at a reasonable time because if I slept

all day what's going to happen I'm just

going to be awake all the next night and

I'm going to be out of my rhythm but

what's interesting is that when I would

wake up then I would be waking up maybe

at 10 10 a.m. in the morning 11: and at

that point if you're sleeping there with

someone like my face you are in a very

REM sleep Desiring state that it's in

those last morning hours and into the

early morning hours when your brain

wants to devour off the menu of sleep

stages this thing called REM in vast

quantities so I was sleep deprived Point

number one second I was going into a

very REM sleep Rich phase in other words

higher likelihood of paralysis and that

occurred to me your description is also

prototypical you've been drinking the

night before went out to the party we

spoke about in one of our previous

episodes that one of the problems with

alcohol is that it's very good at

blocking your REM sleep so you'd been

absent of REM sleep the PRI night you

built up what we call a REM sleep debt

and when you slept all of a sudden what

your brain wanted more because it at

least got some sleep and there you're

going to get mostly your deep sleep the

death on the sheets of your balance

account for sleep was not so great for

deep nonrem but you were very much in

debt with REM so what happened as soon

as you conked out on the couch whoosh

you were probably straight into REM

sleep and then when you woke up you had

this mismatch in timing between

Consciousness and the release of

paralysis what did you experience REM

sleep paralysis love it I mean hate it I

did not enjoy it but I love your

description it's because it makes so

very clear what happened and for those

that have had the experience it can be

mildly stressful to terrifying so thank

you for um providing the therapy that is

knowledge and uh so that people don't

stress it too much but we still dissuade

people from consuming alcohol prior to

sleep correct I want to take a brief

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tracker.com huberman okay so we've been

discussing complete paralysis and of

course that's the inability to

move let's talk about the ability to

move meaning motor learning what is the

relationship between sleep and learning

physical skills either coordination of

motor movement or who knows maybe

increased power output or endurance um

and if you would could you comment on

whether or not there are specific phases

of sleep that are specifically linked to

motor learning yeah great questions so

what we've spoken about so far is that

you need sleep after learning for that

textbook like memory and that is one

category of memory that resides within

your brain there's another type of

memory that you've spoken about which

many of us don't realize is memory and

that's what we call non- declarative or

procedural skill memory so if I were to

you know ask you okay Andrew you know

last night for dinner or yesterday for

lunch do you remember what it was that

you had to eat and my guess is that you

could probably tell me so do you recall

what what some of that my diet is pretty

boring um in the sense I tend to eat

more or less the same thing every day

although I'm open to being flexible

yesterday for lunch I had two grass-fed

hamburger patties maybe a little bit of

rice sliced cucumber some tomatoes and

because I'm a driveby blueberry eater

there were some blueberries out on the

counter and I had several large fistfuls

of those and then I washed it down with

some water and I half mug just like this

of some cold brew sugar-free yerba mate

and I can confirm folks I was there at

the incident and that's exactly what he

had but did everyone who was watching or

listening just realize what happened in

this room today something that Einstein

suggested would never be possible that

Andrew just travel back in time that

using this Incredible Gift of memory you

you folded time almost like a concertina

compressing it and you race back within

milliseconds you were shaking your head

yes I know what I had and you race back

into that catalog of all of your

previous lunches you found the correct

manila folder for that specific lunch

all of the details and out it popped

that is a spectacular complex

computational process that your brain's

memory system accomplished Within

milliseconds it's stunning what we have

as this gift of memory but as I said

there's another type of memory so if I

were to ask you okay how do you ride a

bike it's very difficult there is no

textbook for here is how to ride a bike

the way that you do it when you're a

child is that you are taught how to

learn how to ride a bike by being on it

so if I were to say how cuz I'm a

longtime cyclist how do I take uh a

right turn with my bicycle the obvious

suggestion would be well you turn the

handlebars if you turn the handlebars at

30 m an hour trying to go around a right

Bend you going crash very quickly what

in fact you do is you alter the steering

angle just a little but you

lean and that is what we call non

declarative meaning you can't declare to

me what it is that you know you just

have to show me through action and

behavior this is skill learning and we

use it for things like sports surgical

procedures flying planes there are so

many musical performance as well so many

aspects so we wanted to then say well

sleep is helpful after learning for

fact-based memory but what about this

other type of memory and in truth I

didn't come up with the idea it was

given to me back in the gosh I'm aging

myself in the early 2000s I was back in

the UK I gave a lecture at the for the

decade of the brain which it was back

then and at the end of the course I'd

spoken a little bit about sleep and this

informational processing but no evidence

for motor skill memory and this

gentleman be lovely gentleman Old

Gentleman with a sort of a white beard I

remember his tweed jacket this green Hue

was beautiful and he came up to me at

the end and he said look I'm a musician

I'm a Pianist and I was fascinated by

what you said about sleep sometimes I'll

sit down and I'm learning a new piece

and I just don't seem to be able to get

it and I practice practice and practice

into the evening and then I just stop

and then I come back the next day and I

sit down at the piano and I can just

play do you think that's

sleep and of course at that moment my

mind starts just relexing with ideas and

I'm thinking gosh there's the next 10

years of my work and grants and so I

sort of said look I I think it's a

fascinating hypothesis it could also be

that you're just maybe a little bit

tired in the evening and but it's it's

entirely possible I don't know of any

evidence yet that supports that I

suppose the alternative hypothesis that

there's simply a certain amount of time

that needs to elapse After experiencing

something new that one wants to learn

the trigger for learning is I don't know

some biochemical SL neural signal that's

like a wavefront and it takes a while

for that wave to go ashore which is

learning and that independent of how

much sleep one gets or the quality of

sleep that the learning could occur I

suppose that's one idea no that's in

fact precisely the central hypothesis

that we then set out to test which is

that your maybe it's it's practice then

some time that helps you create that

perfect motor routine that's one

hypothesis but let's split that apart

maybe it's time but time spent awake or

is it time but time spent asleep so we

designed a study to disambiguate between

those two both groups learned a motor

skill task and it's very much like

learning a piano and you learn a

sequence of movements let's just say

41324 and we have you type that out over

and over again for periods of 30 seconds

and then you rest for 30 seconds and

then you do it again you do 12 of those

trials and sure enough practice seemed

to get you better and you were learning

and your learning curve went up and then

we brought those participants back 12

hours later and we retested them on that

same motor memory half of those

participants spent that 12 hours awake

the others had a night of sleep in

between an 8 Hour night of sleep when we

brought the people who had learned in

the morning and tested in the evening

without sleep they had retained that

memory they were no worse they were just

no better but in the people who had

slept

what was stunning was that they had

improved their performance output speed

by 20% and they'd improved their

accuracy by almost

37% wow so in other words it wasn't time

that you needed to produce Perfection it

was time with sleep in other words

you've often heard the statement

practice makes perfect but we violated

that edict it wasn't practice that makes

perfect it's practice with a night of

sleep that makes or leads to perfection

in other words after learning your brain

continues to improve in the absence of

any further practice however that

learning occurs exclusively during

periods of offline sleep and not across

equivalent time periods while you're

awake now what was interesting in the

group that remained awake across those

12 hours

we then actually brought them back after

a further 12 hours but now after a night

of sleep and they showed that beautiful

benefit so the

sleep that can let's say enhance

although I think what we're really

talking about here that consolidates

motor learning yeah can arrive the night

after meaning one finishes let's say

learning at I don't know 11:00 a.m. and

then they sleep later that night or the

following night and in both instances

that sleep can enhance or let's say

consolidate the motor learning that

occurred that's right so it was to your

question actually that we discussed

earlier and I recall now I didn't answer

it which is that you the things that you

learn throughout the day you don't have

to worry about learning them really

close to bedtime so that they're

available and accessible for this sleep

dependent work of sleep after learning

it seems to be that the human

brain and we've plotted this we've

looked at how

at what point does the brain sort of

fail in terms of its ability to place on

hold sort of on the runway ready to take

off into the consolidation phase and it

seems to be about 16 hours MH that you

can hold on to those freshly formed

memories for about 16 hours and then you

get the chance to sleep and consolidate

them so if you learn at 11:00 in the

morning or if you learn at 7:00 p.m. in

the evening don't worry about that those

memories are still going to be gathered

together in the beautiful receptive arms

of sleep and then knitted up and

enhanced when it comes to procedural

memories and by the way that's a key

difference to those two types of memory

sleep will take fact based memories and

simply save them so that you don't

forget it doesn't necessarily boost them

anymore it just simply prevents you from

Forgetting which is what would happen

otherwise across a waking day ah key

point it's it's not enhancement it's

consolidation of or

essentially

um the way I might think about it is the

new information is put into a potential

memory bank and that information is

either flushed or maintained depending

on whether or not you get sleep that's

right there's no enhancement enhancement

would be supranormal levels of memory if

you sleep and that's the case for

textbook like memory in other words

sleep comes in and it stems the blood

flow of forgetting from the memory wound

as it were to get I don't know why it

came up that's a terrible analogy no I

like it I guess we might say Hemorrhage

right like it is okay and but so sleep

comes in and prevents that from

happening but with motor memories it is

enhancement it's that when you're awake

across the day you don't get any worse

which is what happens with fact textbook

memory you hold that performance but

then sleep comes in and it boosts you

even further

you get a nice benefit without doing

anything

further so then the question became to

your point if sleep is doing that if

it's not practice that makes perfect but

practice with sleep what is it about the

sleep so we looked at their sleep

physiology and what we found were two

interesting components first it seemed

to be related to that lighter form of

stage two nonrem sleep I told you that

textbook memory requires deep non-rem

sleep stages three and four casting back

to episode one motor memory more

dependent on stage two and those

beautiful spindles that are the Hallmark

of beginning your stage two the more of

those that you had the greater the

memory benefit the next day we then

wanted to say well is this effect simply

something to do with the

nighttime because that's the other

hypothesis it's not really about sleep

it's just something about night ESS

because in all of the studies i'

described so far they're all happening

at night and at night they were sleeping

so is it really nighttime or is it

specifically sleep so now we did a nap

study with motor skill learning we

repeated that and sure enough even

though that time period was across the

day not during night n they showed this

beautiful motor skill benefit if they

napped versus if they did not and then

in that naps City I was telling you that

they were learning the sequence with the

um right non-dominant hand and they were

all we selected all right handers to to

make it equal and they were typing 41324

41324 and that right hand as well you

know is controlled by the left motor

cortex so after in the nap study when we

recorded their sleep we used very high

density EEG so lots and lots of sensors

on top of the head so we could map with

High Fidelity resolution the surface of

the brain or the surface of the scalp

and infer what's going on in the brain

and what was interesting is that yes

those sleep spindles the more of them

that you had in the nap the better your

motor skill learning was but there

seemed to be a lateralized effect such

that the Sleep spindle activity on the

right side of the brain which controls

the left hand which was not working that

showed no spindle increased in activity

however on the right hand activity that

invoked activation in the left motor

cortex that left motor cortex and

specifically Al the hand region showed a

local increase in spindle activity and

subsequent work and work prior to our

had demonstrated that it's not sleep

physiology globally it's almost as

though your sleep physiology responds to

the mapping of the memory in the brain

wherever the memory is that's where

sleep when you go to sleep sort of

starts massaging the cortex so that you

get that plasticity it's almost like a

good masseuse you know you sort of sit

down they say where are your problem

points and you say it's it's here and

here and so they don't give you a

general massage they go to work on the

regions that have been working hardest

that require greatest attention sleep

does that it's a amazing and reminds me

of some of this work that was done I

think in the late 90s early 2000s

Richard Morris and um colleagues over in

I think he was in Edinburgh

um talked about synaptic tagging you

know this notion that animals or humans

perform or learn some new motor skill

maybe navigation of a novel environment

maybe a motor skill of the 41234 that

you described you know keys on a piano

or something like that and then it was

acknowledged that the the changes in the

connections between neurons don't occur

immediately which meant that there had

to be some sort of tag or label to the

synapsis that marked them for

consolidation later for plasticity

long-term potentiation things of that

sort the names don't really matter um I

think later it became clear based on

Marcus Frank's work and others that

indeed during sleep the hard rewiring of

the nervous system occurs plasticity

occurs but what you're saying is that

there's a high degree of

specificity meaning the specific

circuits that were active and required

for the learning are the specific

circuits that are modified which on the

face of it one could say well of course

what that means is that during sleep the

brain is um somehow able to uh the

neurons of the brain that is are able

to chemically or electrically or both

signal like this is where that there

needs to be some modifications done and

then then like a night crew um the the

brain self- induces its own changes

which is remarkable it really is it's

almost as though there are red flags

that are planted in the territories that

have undergone learning dependent

plasticity and they are calling out

almost like you know hungry mouths that

are in plasticity famine for the feast

relief that comes by way of sleep do we

know what the factors are that are

released in sleep that allow that to

occur or is it I'm guessing there are

many people love to talk about brain

derived neutrophic Factor bdnf but which

is a very interesting molecule but um

it's probably just one of a panoply of

of molecules that are that are important

we we don't know necessarily the

neurochemical processes although some

people have manipulated plasticity and

then blocked it with different types of

nmda which is a certain type of receptor

in the brain for excitatory activity

which is the underlying basis of brain

plasticity so that certainly is

dependent but what's interesting about

the sleep spindles I said in the first

episode that they burst somewhere

between about 12 to 15 times per

second if you apply that type of

stimulation to a particular neuronal

circuit within the brain that seems to

be one of the and it's not the only but

one of the ideal sort of Sweet Spot

tickling of neurons that forces them to

say oh I think I should strengthen this

circuit so it's almost as though these

sleep spindles are ideally designed at

the frequency at the sort of tickling

level of neurons to stimulate exactly

what we think is the underlying basis of

strengthening a memory which is at the

level of the neurons the

strengthening of synapses so interesting

um because we hear this fire together

wire together high frequency

transmission between neurons is what

creates plasticity but this is literally

a replay of previously meaning earlier

that day or the previous day as you

pointed out activity in the given

circuit being replayed not unlike the

the the work that you talked about

earlier the fast replay of neurons in in

the hippocampus but here it's not

necessarily just in the hippocampus it

can be in the neocortex or other

structures that then builds up the uh

the the Vigor with which that circuit

can function in the daytime AKA learning

um is it's super interesting you

mentioned that this is occurring largely

in stage two of sleep not in rapid eye

movement sleep is this business of stage

two being the the main period of sleep

in which motor learning occurs unique to

motor learning in other words cognitive

information um surely can get um wired

into the brain at night but is that

largely Associated just with rapid eye

movement sleep what this would suggest

in other words is that the earlier

stages of sleep 1 and two and heading

into three and four serves a specific

purpose which

is consolidation of motor skills and and

motor learning from the previous one or

two days it does seem to be that stage

two stage one is we now think of more of

a transitional stage but we will speak

perhaps when we discuss the idea of

creativity that it also may have a

memory function that very light first

step of sleep stage two is certainly

related to motor skill in fact stage two

is fascinating we used to think of it as

just the stage that you had to go into

to get to deep sleep and the stage that

you had to go back through to get up to

REM sleep never made any sense to me why

because stage two non-r sleep is about

40 to 50% of your night why would you

spend 40 to 50% of your time asleep when

it's just simply a gate to get to

something better you would spend more

time in the something to something

that's better stages

so we started to find functions and

stage two is dist distributed throughout

the night but those sleep spindles in

stage two are not evenly distributed

throughout the night you get some of

them in the first quarter more of them

in the second quarter of sleep certainly

more in the third quarter but you get a

lot more of those sleep spindles in the

last quarter of the night and in fact

when we looked at the overnight study

where we' had people learn in the

evening tested the next day we recorded

their sleep in between

yes sleep spindles predicted and stage

two predicted how much better they were

the next day but it was especially stage

two in the last quarter of the night

let's say I'm going to bed at I'm just

for argument sake for ease midnight and

I'm waking up at 8 it's in that sort of

6:00 a.m. to 8 a.m. range when I if I

was going to sleep at that time would be

getting my stage two and I find that

interesting because it is the time of

night that we all feel it's okay to cut

short to get a jump start on the day

it's this Modern Life erosion of our

sleep time and what these findings would

suggest is that you are short changing

your brain of some significant motor

memory performance especially those

classic Olympic coaches that have their

Athletes Training until you know 8 in

the evening and then you know they're in

bed by sort of 10 or 11: but they have

them waking up at 5: back on the

athletic field at 6 but they would gain

some additional motor memory benefit if

you just let them sleep a little bit

longer I recall there was a study done

at Stanford relatively small study um

but interesting nonetheless because I

think it was the basketball team that

was asked to um spend I think an

additional two hours in bed there a

sleep extensions today um and they were

even told that they could do other

things in bed uh besides sleep um there

might have been some specifications of

you know things they should not do in

bed during that time um but at least by

self-report some of the students said

that they slept a bit more or they

relaxed a bit more in bed and indeed

when compared to the control group there

was a significant Improvement in their

um I forget if it was three throw free

throw percentage excuse me um or other

metrics of a basketball performance yeah

it was the point scoring performance it

was the speed up and down the court and

it was a great study done by Sher Mah at

uh Stanford University um and she's done

epic work with athletes to to sort of

replicate those findings and the athlete

story is interesting some people may be

saying well didn't you just make a hop

skip and a jump from you know 41324 to

inferring complex motor skill I thought

about that so we did a a new series of

studies where we this is control that's

the nice thing about the sort of typing

on a sequence you can really measure

that performance with high sort of

accuracy but we then switched it to a b

manual task much more like learning to

play a piano and you were learning

sequences that were 12 14 items in

length and you had to learn them over

and over and we had a hypothesis would

sleep fail at the the task when motor

skill performance became much more

complex or would it be different and

what we found was that the more and more

complex the motor skill became the

greater and the greater the benefit of

sleep um by way of that consolidation

effect and then I started to hear

something cuz I would often be in the

room as these participants were learning

the sequence and then as they were

testing and my ears started to hear

something that I I couldn't quite

believe to begin with they would start

to learn these motor

sequences but they would seem to have

these pauses and it's what we call

chunking in motor skill memory so

instead of 41324 41324 they would do

41324

41324 and I would have them be using the

same keyboard and I got to know the

sound of the the keyboard so I could

hear it 41324 41324 and then when they

came back the next day yes they were

performing faster but they weren't just

doing 413 2 4

41324 they were simply doing 413 24 4 3

there was no Gap at all so we went into

the individual responses individual

motor sort of finger responses and sure

enough before sleep there were these

very clear problem points on these pain

points in the motor memory sequence but

then when we came back after a night of

sleep and looked at their data it wasn't

as though sleep simply grabbed the motor

skill memory sort of profile and lifted

everything up sleep was selectively

going after those pain points and

improving them and that to me was

interesting because that's the goal of a

good athlete it is

automaticity you don't want to be

thinking about it at some point you go

from a very conscious Act of

deliberately trying to remember what you

should be doing to then not thinking

about it at all it's only automaticity

that gives you that ability not to think

and it operates below the level of

Consciousness super interesting and here

we're talking about specific changes in

the

brain terms of neural activity Etc that

occur during sleep when we've been

exposed to or engaged in a particular

novel for us motor skill and you see

this you know these spindles in stage

two Etc but does it work the other way

as well meaning does the process of

trying to learn a new motor skill

enhance certain components of sleep or

maybe even one's ability to sleep you

know years ago I heard uh

that

practicing

unilateral leg movements this is a

perhaps a crazy idea but but it makes

sense in the context of what we're

talking about practicing unilateral leg

movements things like you know

everyone's familiar with squats and

deadlifts and things of that sort but

there are some one-legged movements like

a pistol Squad a pistol Squad that's

pretty hard um if one can do them I'm

always impressed um Bulgarian split

squats you know foot up on the bench and

then squatting down with a dumbbell

things like that were just unilateral

movements that require a lot of mental

attention to the performance of that

movement could be in the gym but it

could be something else as well you

think about a dancer trying to learn how

to um organize their their steps um

where they have to pay careful attention

to right versus Left Foot Right they

always say you know like two people have

two right feet that can't people can't

dance have two right feet or two left

feet by the way for those listening

Andrew is looking at me right now when

he's saying two right feet rightfully so

no I I have no knowledge of your your

dancing ability or or or challenges

thereof um as I recall there may have

been some some uh very preliminary data

about changes in

the amount of certain sleep stages

according to whether or not someone had

tried to learn a skill in this case

unilateral uh uh

limb performance the previous day so in

other words if one wants to improve

their sleep would the attempt to learn a

new motor skill be one Avenue to to

improve one's sleep it's it's

interesting if you look at some of the

data it's a little bit mixed in terms of

motor skill learning but there are some

studies demonstrating that it's true for

textbook like memory and there's a study

gosh done many years ago Again by the

great German group of yan born and they

simply ask the question if you were

to just not be learning very

deliberately and intensively through a

textbook like set of information and

then we just measure your sleep to get a

Baseline and then we force you to have a

very long very intensive learning

session of these facts and then when we

measure your sleep again is there any

difference relative to the non-intensive

learning day versus the Intensive

learning day and indeed what they found

was that there was an increase in their

deep non-rem sleep in their deep slow

wave sleep and again we think it's

almost we describe it as a homeostatic

response which is just a fancy way of

saying that when the brain is driven to

undergo a demand then sleep will respond

to try to accommodate that demand and so

I would say that there are probably many

other things and we discussed this in

episode two in terms of a how to

optimize your sleep that probably carry

a bigger bang for your buck in terms of

optimizing and enhancing your sleep but

is there any evidence to suggest that

that's the case there does seem to be

some evidence in the literature yeah so

interesting I I certainly know the

experience of trying to learn a lot of

information and then feeling like my

sleep is that much deeper although I've

also experienced the challenges in quote

unquote turning my brain off when I've

been trying to learn something and then

it's late in the evening forget the

caffeine component you know just that

the the information is spooling in my

head maybe some pre uh test anxiety that

kind of thing so I think the the tools

and protocols that um you offered so

generously in episodes one two and three

are especially important under those

conditions learning how to really taper

off one's level of of thinking and

planning and arousal in the evening

really bring things down so that one can

access that sleep I mean one only wishes

that the more we did during the day the

easier it would be to sleep I think to

some extent that's true but there's a

there's some um there's some conditions

in which doing more thinking about more

and and I guess that's sort of the the

irony right I interrupted myself but on

purpose that wouldn't it be wonderful if

the amount and ease of sleep was

directly proport to how much we needed

to sleep that's that's one of the the

tricks in this whole business system

sometimes right like sometimes when we

really need sleep we're dealing with

something psychologically challenging or

we need to learn something we have an

exam that often can be when it's most

difficult to sleep gets right in the way

of what we need most although coming

back to your point I think physical

activity does seem to be one of those

things that is very good and I'm I I'm

remiss to have not included it in the

optimization or the unconventional tips

there is a very good robust literature

now demonstrating that if you are

Physically Active during the day you can

boost the quality of your sleep

particularly your deep sleep at

night it seems to be there are some

subtle differences in terms of whether

you're doing aerobic versus anerobic so

let's say versus you know doing a spin

bike class for an hour versus lifting

resistance uh or doing resistance

training for an hour or strength

training there's subtle differences but

netet overall the big picture of you is

that when you perform exercise you drive

a response from enhanced sleep

particularly deep sleep at night and I

think many people have had that

experience you've been out on a long

hike maybe a 10 12 mile hike or you've

just been working in the garden doing

really you know sort of long Landscaping

work throughout the day six or seven

hours and you just come in and you go to

bed that night and you you just know

that this is going to be the most Royal

night of sleep that you could you know

it ahead of time you know sort of

earhole to to Elbow um and that evidence

is now very clear the the one

interesting thing if you dig into that

data though you can drive increases in

deep Sleep by way of exercise it does

seem to come at a little bit of cost to

REM sleep exercise May throttle back

some of your REM sleep now don't fear

that it may just simply be that every

night and we know this my sleep and my

stage stages of sleep are going to be

much different to to yours in how they

are structured and how they play out but

even within me the same individual Matt

my sleep stages vary from one night to

the next to the next some of that is

idiosyncratic others are or other

reasons depend on what I've been doing

during the day and so it may be that we

don't need to get concerned about that

modest reduction in rem due to exercise

enhanced non-rem because it's simply

that when you've gone through that form

of activity as a human being during the

day what you need is that type of sleep

more so than perhaps REM sleep and

therefore the next night things

calibrate back down let's say I wasn't

as active I just sort of went to work

durly and I'm back to Baseline again so

I don't get too concerned about that but

I just want to bring it up it's there in

the literature yeah I think it's a very

interesting point and one just has to

trust that nature Knows Best in

modifying the percentage of different

sleep stages according to our daytime

activity again highlighting the the key

uh relationship I mean the the closely

tethered relationship between daytime

activity and sleeve and vice versa

correct yeah and it's a it's a

reciprocal Loop because what we found is

that exercise during the day can enhance

sleep at night but also what we found is

that sleep at night enhances your

athletic performance the following day

and I'm not just talking about motor

skill memory upstairs in the brain I'm

talking about physical activity in the

body and if you limit sleep to let's say

less than 6 hours the data demonstrates

that your Peak muscle performance is

decreased your Peak vertical jump height

decreases your time to exhaustion

decreases by in some studies it was up

to 30% so if you're training for a 10K

Marathon but you don't get enough sleep

the night before you're done by seven we

also know that it decreases perhaps more

than almost any of those and it's

striking the brain's motivation to

exercise at all so in fact many people

may be able to get close to their Peak

muscle strength when they are underslept

chances are they're probably never going

to get to the chance to express that

because their motivation to exercise

just drops off and I think many people

will resonate that you had a bad night

of sleep I just don't want to go go to

the gym the next day the final part of

that is injury risk there is a

significantly elevated injury risk and

if you ask most athletes okay what am I

particularly concerned about is it my

performance or if I had some kind of

injury that knocks me out for the rest

of the season and so I've had the

fortunate chance to work with many

professional teams uh of different kinds

and gradually they are realizing what

I've sort of long said and it's a crash

statement but I think sleep is probably

the greatest legal performance-enhancing

drug that most athletes are not abusing

enough I could not agree more I mean I

feel like every time I say sleep is the

Bedrock of mental health physical health

and performance it

um it's sometimes perceived is just kind

of like oh yeah sleep we need to sleep

um but there's no question that it the

positive effects of getting excellent

sleep on a consistent basis um far out

way and perform any kind of

supplement or even performance enhancing

drug in fact those Mo most supplements

and performance enhancing drugs that can

indeed improve performance of various

kinds seem to only function or function

best certainly on a backdrop of

excellent sleep and I should say that

you I think you've done a brilliant job

of being very explicit about the fact

that you need to get all of the basics

in place and then it's great to think

about fine tweaking with optimization of

things like supplement ation and all of

these other things and I think sometimes

that message has been maybe a little bit

more mixed in the social media

environment that we often don't think

about the basics and we go straight to

supplementation where you would say gosh

there's actually a log order of

magnitude benefit that's on the table if

only you to do some of the basic things

that your your grandmother would

probably tell you you know eat right get

your stress sorted out do some physical

activity and make sure that you get some

sleep do those things and you're very

far along now there's more opportunity

on the table for fine tuning as as

you've elegantly discussed but I think I

just want to acknowledge that I think

you've done a really great job of being

balanced in that message um and I hope

people um in the general sphere can

appreciate how hard that is to do it's

not an easy thing when you are talking

about supplementation because at first

it sounds as though gosh all of this

speak and you describe great data means

that it is the Holy Grail

of enhanced human beings but you're

always careful to say this after the

foundation and I can give a very good

example with sleep let's say that you're

trying to manage your weight and lose

weight and you're dieting but you're not

getting sufficient sleep what we've

discovered is that yes you will lose

weight when you're dieting even though

you're not getting enough sleep the

problem is that almost 60% of the weight

that you lose will come from lean muscle

mass

and not fat in other words when you are

underslept and dieting you keep what

you're trying to lose which is the fat

and you lose what you wish to keep which

is the muscle so your body does

something very interesting in its um

removal of different types of energy

stores in your body when you are not

slept it becomes very stingy with fat

and it will not give it up when you are

sleep deprived which is very why would

that be by the way muscle such a

metabolically demanding tissue you know

if you're you're send by not sleeping

well you're sending signals that there

really isn't the capacity to take care

of what you already have much less uh

increase the size of the engine that's

exactly right and then think about fat

which is in terms of its energy you know

unit benefit it has you know at least

perhaps twice the caloric value that

protein does so if you are underslept

that is a warning sign to any

evolutionary species past that things

are dire so whatever I'm going to do

this is break glass in case of emergency

situation and if you're not getting

enough calories I'm going to hold on to

the thing that has the highest caloric

value right until the end which is fat

and I'm going to give away the stuff

that doesn't have as much caloric

benefit because I am in a caloric

deficit right now now of course that's