Using Caffeine to Optimize Mental & Physical Performance | Huberman Lab Podcast 101

ANDREW HUBERMAN: Welcome to the Huberman Lab podcast,

where we discuss science and science-based tools

for everyday life.

[MUSIC PLAYING]

I'm Andrew Huberman, and I'm a professor

of Neurobiology and Ophthalmology

at Stanford School of Medicine.

Today we are discussing caffeine.

Caffeine is one of the most widely used substances

on the planet.

Estimates are that more than 90% of adults and as many as 50%

of kids that is adolescents and teenagers

use caffeine on a daily basis.

Caffeine is an amazing molecule.

Most people are familiar with caffeine's ability

to increase alertness and to reduce our feelings

of sleepiness and fatigue.

And indeed, it does that.

But what most people are not aware of

is that caffeine acts as a strong reinforcer.

What I mean by reinforcer is that, when caffeine

is present in a drink or food--

and yes, indeed, caffeine is present in many foods

even unbeknownst to us.

When it's present in drinks and foods,

we actively come to like those foods and drinks more than

if caffeine were not contained in those foods and drinks.

So it reinforces our liking of particular foods and drinks.

And indeed, it even reinforces our liking

of the containers they are consumed from

and the company we keep when we consume foods and drinks that

contain caffeine.

That is, caffeine is not just a stimulant.

Caffeine is a reinforcer.

And it's a reinforcer that plays an active role in almost

everybody's daily life.

We can say that with confidence because, as I mentioned

a moment ago, more than 90% of people are consuming caffeine.

And most people think that they consume caffeine because it

makes them feel more alert.

But there are many reasons why you're consuming caffeine.

And I'm not going to tell you that consuming caffeine is

necessarily bad.

In fact, today, I'm going to tell you about many

of the positive health benefits of caffeine,

including neuroprotective effects,

antidepressive effects, and certainly

performance-enhancing effects, both for mental performance

and for physical performance.

Now that said, there are certain situations in which you

want to avoid caffeine, and there are certain people who

might opt to avoid caffeine.

That's especially the case when one thinks about caffeine

not just as a stimulant but as a reinforcer.

In fact, caffeine is such a strong reinforcer

that, if even tiny amounts of caffeine

are present in certain foods and drinks,

you will very quickly come to prefer those foods

and drinks over other choices, which

can be a good thing or a bad thing,

depending on what sorts of food and drink choices

you're trying to make.

So today, I'm going to inform you

about how caffeine works at a mechanistic level.

I promise to do that with a minimum

of nomenclature and such that, even if you don't have

a background in biology, you will

be able to digest that information easily.

And then I'll tell you how to use caffeine to your advantage

or conversely how to avoid caffeine at certain times

to your advantage.

So today's episode will focus both on mechanisms and tools

that is the use and leverage of caffeine

to improve mental health, physical health,

and performance.

Before we go any further into today's discussion,

I want to tell you about some recent results about a molecule

that's found in certain caffeinated beverages

and that has been proven to be very useful for both weight

loss, mental performance, and controlling blood sugar levels.

And that's GLP-1 or glucagon-like peptide 1.

Glucagon-like peptide 1 is found in the brain and body.

It acts both on the brain and body.

It does many different things.

But one of its primary effects that's been discovered

is to reduce hunger.

And it does that in two ways.

It does that by activating certain neurons

in your hypothalamus.

So that's a brain region that controls hunger and satiety.

It makes us feel full at the level of the brain,

so it makes us feel sated, that is.

And it actually makes us feel full.

It turns out that GLP-1 acts on certain receptors in the gut

to make us feel as if we've ingested enough food.

It doesn't necessarily make us feel

as if our gut is distended, but it makes us feel full.

That's really interesting because, if you

think about it, when we eat, our stomach fills up, obviously.

And that information has to be communicated to the brain such

that the brain can then send satiety signals that actually

shut off our hunger.

And believe it or not, the brain actually

activates signals to reduce the desire

to chew when our stomach is full.

And GLP-1, as I mentioned, works on the brain

to create these feelings of satiety as if we've had enough

and to reduce our desire to eat more.

And GLP-1 acts directly on the gut

to give us a slight sense of fullness in the gut, which then

is communicated to the brain.

So really, there are two parallel signals

being sent when we have GLP-1 present in our system.

Now a little bit of relevant history on GLP-1.

It was actually discovered in Gila monsters.

These are these reptiles that can go long periods of time

without eating.

And a very clever scientist decided

to study why it is that certain animals like Gila monsters

can go a long period of time without ingesting anything.

And it's because they produce very large amounts of GLP-1.

They isolate the peptide from GLP-1,

then they looked for the analogous peptide in humans.

And it turns out that does exist.

And as I mentioned, it's released in both brain and body

to make you feel full and sated.

Why am I telling you all this?

Well, today we're going to talk about caffeine.

And there's one particular caffeine source,

which is yerba maté, and there are some other forms of teas

similar to yerba mate that stimulate the release of GLP-1

significantly.

There are also nowadays drugs which are called analogues

of GLP-1.

So these are drugs that mimic or are

identical to the kind of GLP-1 that you would make.

And those drugs are proven to be very effective

for the treatment of certain forms of diabetes

and for the treatment of obesity,

but they trigger enormous amounts

of GLP-1 pathway activation.

So those are extreme cases for people that are really

struggling for weight loss.

But the clinical trials and the data that are out there

in the general population now are very,

very promising for GLP-1 analogues.

Yerba maté tea, provided it's not the smoked variety--

and I mention that because a number of people have cued me

to the fact that yerba maté teas come in smoked varieties

and nonsmoked varieties.

And the smoked varieties are thought

to perhaps be carcinogenic.

That is, procancer-causing.

So I advise people to avoid smoked varieties of yerba maté

tea.

But yerba maté teas are known to stimulate significant amounts

of GLP-1 release.

And so they can be effective as a weight loss tool,

mainly by blunting appetite.

And again, they do that both at the level of the brain

and at the level of the gut.

Now all of what I just told you has

been known for some period of time,

but there are new set of findings that were just

published in Cell Reports Medicine, Cell Press

journal, excellent journal--

which indicate exactly how it is that GLP-1

stimulates both satiety and can trigger additional weight

loss through other mechanisms.

And I find the mechanism to be really interesting and actually

really important, given some other topics we've

covered on this podcast before.

So the basic finding is that GLP-1,

whether or not it's stimulated through the release of analogue

drug that one is prescribed or by drinking yerba maté tea,

for instance, and stimulate release of your own so-called

endogenous GLP-1, yes, it makes you feel more full at the level

of brain and body.

But it turns out it also stimulates thermogenesis.

Now thermogenesis is the active utilization

of more metabolic energy.

And fat cells, in particular-- so-called beige and brown fat

cells--

are a potent source of thermogenic activity

in your body.

The basic background is that you have white adipose cells, so

white fat cells.

You have beige fat cells, and you have brown fat cells.

And the beige and brown ones are fat cells

that you actually want more of.

They are not abundant under your skin.

They're abundant really around your clavicles

and your upper neck.

They are the ones that generate heat.

And the beige and brownness of them

is actually the consequence of having a lot of mitochondria

in those cells.

When GLP-1 is elevated in your system,

it turns out that it communicates

to those white fat cells and helps convert them

into beige and brown fat cells.

That is, it takes fat cells that are not

doing anything useful for you except being stored energy.

And I think most people out there

would like to have fewer of those white adipose cells.

There are few of you out there that actually

need more of them that are too thin, too lean,

but most people are suffering from having too many

of these white adipose cells.

Well, when you ingest yerba maté tea or you were to take a GLP-1

analogue or stimulate GLP-1 in any number of different ways,

yes, you stimulate increased satiety,

but you're also stimulating the conversion of these white fat

cells into beige and brown fat cells,

which makes you more thermogenic and over time raises your basal

metabolic rate.

So you're burning more calories even at rest.

It also makes you feel as if you're

more comfortable in colder environments at rest.

This is very much the same as the mechanism that's

induced when you were to, say, take a cold shower

or do regular ice baths or get into cold water regularly.

That, too, stimulates the conversion of white fat cells

to beige and brown fat cells.

So I like these findings very much

because they provide a mechanistic coherence.

They provide that is a really nice story as to how

something like GLP-1 could be so effective for weight loss.

Yes, on the one hand, GLP-1 is reducing appetite,

and that, of course, will help people maintain or lose weight.

But it's also increasing basal metabolic rate.

And we now know how that's accomplished.

It's likely accomplished at least through this one

mechanism by the stimulation of conversion

of these white fat cells, which don't do much for us

except as energy storage units to these metabolically

mitochondrial-rich beige and brown fat cells,

which you can think of as sort of the oil in the candle

that allows your furnace, your metabolism to burn at a higher

temperature and a higher rate.

So that's the mechanism.

And the basic tool takeaway is that,

if you are somebody who's interested in losing weight

and you want to leverage the GLP-1 pathway,

drinking a cup or two of yerba maté tea early in the day would

be a great way to stimulate GLP-1 release.

There are other ways to stimulate GLP-1 release.

You can get it through certain forms of exercise.

In particular, fasted exercise.

This is actually a vote in favor of fasted exercise.

There's a debate as to whether or not

fasted cardio burns more fat than nonfasted cardio.

And the data basically say no, it doesn't really matter.

But that doesn't really take into account

the longer arc of things like GLP-1 release,

so that needs to be taken into consideration.

So you could do fasted cardio.

You could drink yerba maté tea, keeping in mind that yerba maté

tea does contain caffeine.

We'll talk more about the specific forms of stimulants

including caffeine that maté has.

But maté would be a great way to stimulate GLP-1 release.

And then, of course, for those of you that are interested

in more robust activation of GLP-1,

then perhaps you might want to consider some of the new

prescription GLP-1 analogues that are out there.

But that's a more severe stimulus for GLP-1, of course.

And for everybody, regardless of whether or not you're trying

to lose weight, gain weight, or maintain weight,

I think we're going to be hearing a lot more about GLP-1

analogues and drinks and supplements and things of that

sort that stimulate GLP-1 in the very near future because it

does appear to be a very important biological mechanism.

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

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Let's talk about caffeine.

So as I mentioned earlier, caffeine

is consumed by basically most all adults every single day

and consumed at very regular times each day.

In fact, if you were to take a look at your caffeine intake

or the caffeine intake of somebody close

to you, what you would realize is

that they don't do so well if their caffeine intake arrives

even 10, 20, or 30 minutes past their expected or usual intake

of caffeine.

That's pretty remarkable, and it brings

to mind ideas that we are all, quote

unquote, "addicted to caffeine" or that caffeine is somehow

bad.

I'm certainly not going to make the argument that caffeine is

bad.

First of all, I'm a regular caffeine user.

I wouldn't call myself a caffeine abuser,

but I am a regular caffeine user.

And caffeine is known to have certain health benefits.

I listed off a few of them earlier,

but I'll mention those again now before going forward.

Caffeine is known to have certain neuroprotective

effects.

And that is because of its ability

to increase neuromodulators, such as dopamine,

but also other so-called catecholamines

like norepinephrine.

If you don't know what those names mean,

these are molecules that increase levels of alertness,

motivation, and drive.

And so then therefore not surprisingly the large scale

analyses of the relationship between depression and caffeine

shows that, provided people are not drinking so much caffeine,

that it makes them overly anxious,

that regular intake of caffeine is inversely related

to levels of depression.

So it may have some antidepressant effects.

And those could be direct or indirect.

What do I mean by that?

Well, you can imagine that if people are ingesting caffeine

and they are more motivated to do work and pursue

quality social interactions, then

the probability that they will have depression could be lower.

It could also be that there are direct effects

on the chemical systems of the brain that

relate to mood and well-being that could offset depression.

It is not clear whether or not the effects

of caffeine in countering depression

are direct or indirect.

Nonetheless, there's a relationship there,

and it's an interesting and positive one.

Or I should say negative correlation,

positive effect overall on mood and well-being, to be exact.

Now it's also the case that caffeine

can improve mental performance and physical performance.

This has been demonstrated in tens of thousands of studies.

I will review a few studies on this, in particular, today.

But to just give you a sense of how

caffeine works at the level of its timing and impact

on mental performance and physical performance, when

we ingest caffeine, provided that we don't have

a lot of food in our stomach and that our blood sugar isn't

particularly high, generally, we experience an increase

in alertness within about five minutes.

And that increase in focus and alertness peaks

around 30 minutes after ingestion of caffeine

and persists for as long as 60 minutes.

Now this is assuming that one takes caffeine in pill form

or drinks the entire caffeine drink

within a short period of time.

But a little bit later, I'll talk

about how you can consume caffeine at regular intervals

while doing mental work or physical work in a way that

can further increase mental performance

and physical performance.

But let's just touch on what caffeine

intake really does for mental performance

and physical performance.

Perhaps the most robust finding across all

of the studies that I've examined

is that caffeine reduces our reaction time.

That is, it improves our reaction time.

It doesn't make it longer.

It makes it shorter.

So for instance, in a laboratory study

where people were asked to hit a lever every time they hear

a tone, you can greatly reduce the time between the tone

and the pressing of the lever if people ingest caffeine

about 30 minutes before they do that task.

Now that seems like a trivial task,

but this is also seen in the domain of sports performance

and even in cognitive performance, where

people have to arrive at a particular answer

to a question.

And the answer to that question has

to be pulled from their memory banks

within their brain, their hippocampus,

for instance, a brain structure involved in memory.

And if you are asking people, for instance,

to remember the capitals of different states or cities

or to remember certain historical facts,

they will do that at a particular rate.

But if they've ingested caffeine within the hour prior,

their ability to recall that information

is much, much better.

They are faster, and it does not appear

that accuracy is reduced.

In fact, in many cases, accuracy is enhanced.

And that's because caffeine both works on the reaction time

systems of the brain and body.

I'll talk about the mechanisms for that in a little bit.

But it also stimulates certain neurotransmitters

and so-called neuromodulators within the brain and body

that give the neural circuits in the brain that

are associated with learning and memory a lower

threshold to activation.

What does that mean?

That means that we are better able to access

the brain circuitry involved in learning and memory

when we have a certain amount of caffeine circulating

in our system.

So this makes caffeine an incredible

performance-enhancing compound.

And I could give you tens of thousands

of examples of this in humans.

But before I do that, I want to just touch

on what we know about the existence of caffeine in nature

and what the existence of caffeine in nature

and its effects on other animals tells us about what

caffeine does in humans.

Because as I alluded to earlier, what caffeine is doing

for us is not just making us more alert,

improving our memory, improving our reaction time, and so on.

It's actually acting as a powerful reinforcer

of experience.

And it's acting as not just a powerful reinforcer

of the caffeine-containing drink that we drink

but also the mug that it's contained in,

plus the person that we might be sitting

across from when we consume that caffeine, and so on and so

forth.

If it's a little bit hard for you

to conceptualize what a reinforcer is

and why I'm calling it a reinforcer,

let me spell it out in three specific ways.

We often hear about the word reward,

and we think, OK, if we do certain things

and we like the outcome, then those certain things

are rewarded.

Right?

If we're doing something, we receive praise.

The praise is the reward.

And therefore, we are more likely to do

that thing in the future.

In fact, a lot of parenting is like that.

And a lot of life is like that.

However, when we hear the word reward,

we often think about something that feels good to us.

And certainly, if we've worked hard and we get some praise,

that's natural for the praise to feel good to us.

Or for instance, if we work very hard

and we get a certain outcome--

a trophy, a financial outcome, a degree outcome, recognition,

et cetera-- all of those can act as rewards,

but those are all conscious rewards.

We are aware that they are happening.

Reinforcers are a little bit different because the word

reinforcement can apply to conscious rewards of the sort

that I just described, but there are also

many ways in which caffeine stimulates

the release of chemicals in our body that act as reinforcers.

But those reinforcers are subconscious.

That is, we are not aware that they

cause this preference for the activities that

cause their release.

So the study I'm about to describe beautifully,

I believe, encapsulates how is it

that humans came to consume caffeine

and why caffeine exists in nature and the powerful effects

of caffeine as a reinforcing agent both in animals, insects,

and in you and me.

And the title of the paper is "Caffeine

and floral nectar enhances a pollinator's memory of reward."

Keep in mind that caffeine is made from plants.

Some of you will say, duh, but I think some of us

don't realize that the reason why there is caffeine in coffee

is because coffee comes from a plant.

It's a coffee bean, certain teas,

which, of course, are plants that people brew.

Caffeine is contained in those teas, such as yerba maté.

Well, why would this bitter substance-- because,

in fact, caffeine is quite bitter in high concentrations.

Why would this bitter substance be something

that insects or animals would want to consume at all?

It turns out that, in most plants,

caffeine is present in small enough quantities

that insects and other animals-- and in fact, we can't actually

taste the caffeine.

If I were to give you a little bit of pure caffeine,

yes, it would be a stimulant for you,

but you would say that it tasted awful.

It's in a category of compounds that would strongly stimulate

the bitter receptors on your tongue

and would make you cringe and pucker

and essentially walk away from whatever it is that contain

that caffeine and from the experience that

contain that caffeine.

Well, in nature, caffeine is present in very low

concentrations or is masked by other flavors

within flowers, beans, and plants.

And what this paper really points to

is that caffeine in nature is acting

as a reinforcer for bees that are consuming different nectar.

So the way that it works is that bees, of course,

go from flower to flower, and they are consuming the nectar.

They are bringing nectar and pollen back to the hive,

and that provides critical nourishment for the bee colony.

The bees are foraging in a way that includes information

about color, in particular, ultraviolet color, things

that we can't see but they can see,

because they have different photoreceptors than we do.

And what the study shows is that plants and nectars that

contain very small amounts of caffeine

are the preferred sources of food for bees.

And the study is beautiful because they

were able to confirm that they could mask the caffeine taste.

So they know that the bees are not preferring

the taste of caffeine.

But what they do is they pair caffeine

with different food sources for the bees,

then they remove the caffeine.

And what they find is that the bees very strongly

prefer flavors that contain caffeine,

not because they could taste the caffeine but rather for the way

that those caffeine-containing flavors made the bees feel.

So how do those caffeine-containing flavors

make the bees feel?

The same way that they make you and I

feel, a little bit more alert and thereby

able to do more work.

For the bee, the more work is the consumption

of more food, which then has a further reinforcing effect.

So what we're really talking about here

is the fact that A, caffeine exists in nature, in plants.

It exists in concentrations that are very low, so low, in fact,

that they are not detectable to the taste receptors of insects,

and, in many cases, to the taste receptors of humans.

And, of course, there can be high levels

of caffeine in a plant.

But if the plant also contains compounds

that mask the flavor of caffeine,

well then, those plants are going to essentially

be even stronger reinforcers for the flavor of the plant, OK?

So now we're talking about strong flavors

plus strong neurostimulant effects of caffeine.

And the most important point here

is that all of these effects of caffeine are subconscious.

It is not because the bee or you likes the taste of caffeine.

In fact, most people, when they take their first sip of coffee,

they find it taste bitter and kind of noxious.

They don't like it.

You may not even remember that because it happened so long ago

and because caffeine is such a strong reinforcer

that very quickly you come to like the taste of coffee.

You might even come to like the feeling of your mug

in your hand.

You might even come to like the smell of coffee

and so on and so forth.

And that's because caffeine stimulates

the release of certain neurochemicals in the brain,

in particular, dopamine and acetylcholine,

two neuromodulators that increase our focus

and alertness and our feelings of well-being.

A little bit later, I'll tell you

that caffeine stimulates the release of dopamine

in a way that's very much distinct

from the classical dopamine pathway associated

with addiction and reward.

In fact, we can think of caffeine

as having a somewhat privileged access to the reward systems.

I'll give you a bit of a hint of where this is going.

Caffeine stimulates the release of dopamine and acetylcholine

not within the classic so-called mesolimbic reward pathway.

That's just fancy nerd speak for the reward

pathways of the brain.

They're associated with things like sex and food

and drugs of abuse, like cocaine and methamphetamine.

But rather, caffeine seems to stimulate

the release of dopamine in the parts of the brain that

are associated with alertness and cognition,

meaning the forebrain.

This is very important.

We have multiple dopamine systems in the brain and body,

and caffeine seems to stimulate dopamine directly

within the components of the brain that are associated

with clarity of thought and well-being,

but more so clarity of thought.

Now, I'm also talking about caffeine

as a strong reinforcer in that it makes you feel good overall.

And it does.

And that suggests that it also taps into the more

classic reward pathway.

But it does that in a very interesting and frankly almost

diabolical way.

When we regularly ingest caffeine,

it stimulates the increase in dopamine receptors

at multiple sites throughout the brain but, in particular,

within the reward pathways of the brain.

So not the areas of the brain that

are associated with focus and clarity of thought

and cognition.

It does that, but it is also increasing

the level of dopamine receptors in the reward pathway.

And what that means is that, for any dopamine that's

released in response to a positive experience,

social experience, or any number of the other things

that can stimulate dopamine release,

there are more receptors, more parking spots,

if you will, for that dopamine to arrive at

and to exert its increases in mood, increases in motivation,

and overall feelings of drive and excitement.

So there are four ways that caffeine works

that we need to understand.

First of all, caffeine acts as a reinforcing agent.

It increases the probability that you

will return to and engage in a certain activity

or consume a certain beverage or food.

Second of all, caffeine increases

dopamine and acetylcholine, which

are both neuromodulators in the forebrain, which

helps us improve our ability to think, to modify our rule sets.

That is, to adjust our strategies

for different social situations and mental demands

and physical demands.

And third, it increases the number and efficacy

of dopamine receptors in the reward pathways of the brain.

That is, it makes things that would feel pretty good

feel even better.

And fourth, caffeine acts as an antagonist

to adenosine, which offsets the sleepiness that we would

otherwise feel from the accumulation of adenosine that

occurs as we are awake for more and more hours

throughout the day.

So let's talk first about caffeine

as a reinforcing agent.

Again, this was first most beautifully demonstrated

in this study on honeybees where the bees prefer

nectars that contain caffeine.

And that all makes perfect sense in terms

of the ecology of bees and flowers that contain nectar.

There's an advantage, at least in terms of adaptation,

that the flower benefits because of distribution of things

from the flower, which is good for the flowers and the bees

benefit, because they're getting food.

And so there's a kind of a symbiosis there.

But with humans, we're consuming caffeine-containing beverages

for our sake.

I don't think we have it in mind,

nor do the bees have it in mind, frankly,

that we're trying to preserve the plants that

provide the caffeine.

I think we would all suffer, or I should say 90% of adults

would suffer greatly if all the caffeine-containing coffee

and tea plants were gone, certainly.

But most of us are not consuming coffees and teas

and caffeine-containing foods because we're

thinking about the plants they come from

and we want to help those plants.

We're thinking about how we want to help ourselves.

And yet the point of the reinforcing effects of caffeine

are that they are largely subconscious.

We are not aware of them.

Now you might say, no, that's not true.

When I drink caffeine, it makes me feel really good.

So I'm aware that it makes me feel good.

In order to illustrate how reinforcement really works,

let me give you the counter example, which

would be an aversive agent.

So we have reinforcing agents and we have aversive agents.

Let's say that there were compounds in nature that exist

in plants that are aversive.

And indeed, they are.

And let's say that these compounds

were present at such low concentrations

that you couldn't taste them.

Let's say you wake up in the morning

and you go to your refrigerator and you open it up

and you are thirsty, and so you reach

for a nice rich red-containing beverage in a glass jar.

Maybe it looks like cranberry juice or something

of that sort.

Or even a nice clear glass of water.

It looks like a jug of water or a glass of water,

and you drink that.

Taste fine to you.

Maybe even tastes great to you.

And then let's say about 30 minutes later,

you feel a little queasy, you feel a little off,

you feel like going back to sleep,

you just don't feel very good.

You don't know why, but your nervous system

is a predictive machine, and it has a process in which it back

integrates.

Or I should say integrates backwards

into your immediate experience that preceded that not so

good feeling.

We can reliably say that there is a much lower probability

that the next day when you wake up

that you would reach for that same beverage

or for that same container even.

And maybe if you're in a novel environment,

maybe you're staying in an Airbnb or a hotel or something

of that sort, you might even find that you don't really

like the kitchen in which you consume that beverage

in the first place.

And you don't know why.

And unless you got very, very sick the day before,

it's unlikely that you would have such a strong response

that you would entirely avoid, for instance, water or glass

jars containing liquids, et cetera.

Let's say you went back to the refrigerator

and you consume a beverage again and you just

didn't feel so well, you felt less good

than you normally would.

Well, even without any ability to taste

what's in that beverage and even without any understanding

of what was happening to you at a conscious level,

there is a very, very high probability

that you will avoid drinking that particular beverage

and certainly at that location and in the same volume

in the subsequent days.

That's just the way that aversive agents work.

And they work by way of activating neurons

in the gut that communicate with areas in the brain that give us

this feeling of queasiness.

And for some of you hearing this,

that pathway and that association

with times in which you felt queasy and as if you wanted

to vomit is so powerful that you might even be feeling

some of that symptomology now.

For certain people that's going to be increased salivation

which precedes vomiting, we know that there's

a class of neurons in the brain relate

to an area called area postrema that actually stimulates

vomiting.

And if I keep talking about this,

I'll probably feel like I want to vomit,

so I'm going to move on from this in a moment.

So when we ingest caffeine-containing beverages

and foods, it's the exact opposite scenario

as to what I just described.

Caffeine, as a reinforcer, makes us

feel slightly better or a lot better

in the immediate minutes and hours after we ingest it.

So it's acting as a reinforcing agent

not just while you are under the effects of caffeine

but for the things that preceded the ingestion of caffeine,

which is why you return again and again

to caffeine-containing beverages, such as coffee

and tea or maybe even foods that contain caffeine,

even if the taste of those foods is not something

that you would otherwise consider, especially delicious.

In fact, most people when they take their first sip of coffee

or tea or other caffeine-containing beverage,

they find it to be very bitter.

And that's not because of the taste of caffeine.

It's because of the taste of the beverage itself independent

of caffeine.

However, when caffeine is present in there,

they come to prefer that taste over most all tastes.

In fact, they will, as I mentioned earlier,

will invest a lot of financial resources and time and energy

to make sure that they get that beverage.

What they're trying to make sure is not that they get that taste

but that they get the caffeine.

It is that positively reinforcing.

And the taste therefore takes on new significance, new meaning,

and we come to associate it as positive.

And in fact, most of us, including myself,

love the taste of espresso, love the taste of coffee,

love the taste of yerba maté even if the initial taste,

the very first time that we consume that beverage,

was either neutral or negative.

And that is all because of the reinforcing properties

of caffeine.

And then, of course, there are the more direct actions

of caffeine.

That is, the faster actions of caffeine.

And just to list those off again very briefly so that you

have them in mind going forward, caffeine also

increases the release of dopamine and acetylcholine,

both of which are neuromodulators

in the forebrain, which increases clarity of thought

and your ability to rule switch, your ability

to move from one context to another

and change and understand the rules of engagement,

social engagement, physical engagement, mental engagement,

and so forth.

And as I mentioned before, caffeine also

increases the number of dopamine receptors in the reward

pathway, such that any good thing that happens to you.

Any positive experience that you have

will have a more potent effect on your feelings of well-being.

And last but certainly not least, caffeine

acts as an adenosine antagonist.

It reduces your feelings of lethargy and fatigue

and your desire to sleep by parking

in the receptors for adenosine and not

allowing adenosine to have its pro-sleepy, if you will,

effects on your brain and body.

I'd like to take a quick break and acknowledge

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I'd like to just briefly talk about adenosine and some

of its molecular features.

And again, if you don't have a background in biology,

don't worry.

I promise to make this very clear to everyone.

First of all, caffeine is what's called a methylxantine.

It's a plant alkaloid.

That's why caffeine itself is very bitter.

Again, if I were to give you just the tiniest

little bit of pure caffeine, you would find

it to be extremely aversive.

So these plants that have snuck small enough amounts

of caffeine into them or that have

masked the flavor of caffeine with other flavors

such that bees and humans want to consume them,

while we don't know what plants think, it does

seem very diabolical and very clever

in that we are seeking out these caffeine-containing plants,

beverages, and foods even though caffeine itself

is this alkaloid that is very, very bitter.

Methylxantine-- that is caffeine--

binds to adenosine receptors.

And there are really two types of adenosine receptors.

There are these so-called A1 receptors and the A2 receptors.

And they are present in different parts of the brain

and body at different levels.

We don't have to get too far into receptor subtypes.

More importantly to understand is

that adenosine makes us feel tired because of the way

that it taps into the ATP pathway.

The ATP pathway is central to energy production and feelings

of overall energy in our brain and body

in all cells and organ systems.

When caffeine binds to adenosine receptors,

it prevents adenosine from breaking down

certain components of the energy production pathway.

And the net consequence of that is increased cyclic AMP.

So basically, when we ingest caffeine,

we are biasing our system towards

the pro-energetic aspects of these cellular pathways.

Now it's really important to understand that, in biology,

even if you block a receptor or you prevent

the activity of an enzyme and--

at least, in this case, you end up

with more cyclic AMP, more energy.

You're not really getting more energy.

You're actually borrowing energy against an overall system

that is frankly nonnegotiable.

What do I mean by that?

Well, let's say that you were to wake up after six or eight

hours of sleep and to drink a lot of caffeine

and keep drinking caffeine throughout the day blocking

those adenosine receptors.

Yes, you'll offset fatigue.

You'll offset sleepiness because that adenosine simply

can't function.

But at the point where the caffeine becomes dislodged

from the adenosine receptors, you

will have a massive glut, a backlog of adenosine,

and you will feel extra, extra sleepy.

So really, there's no way to create more energy

in your system.

Really, what you're doing is you're

changing the timing in which the sleepy signals and the more

energetic signals are arriving.

And this is really important to understand as the backdrop

to the various tools that we're going

to get into next, in which you can use caffeine for enhancing

mental performance and physical performance

and other aspects of health.

But it's very important to understand this concept

that, when you wake up in the morning provided that you slept

well and enough the night before,

your levels of adenosine will be about as

low as they will ever be.

Actually, in order to get your adenosine levels really

bottomed out, you want to avoid caffeine in the first 90 to 120

minutes after waking.

We'll talk about why that is because it turns out

there's a way to completely clear adenosine

out of your system in the hour or so after waking.

But for most people, adenosine levels

are going to be close to their lowest

after a good night's sleep.

But there's really no negotiating the accumulation

of adenosine that's going to occur

and going to bias you towards feeling more sleepy than you

would.

Otherwise, that's going to occur throughout the day.

There's really no way to eliminate adenosine.

All you can really do is block its function.

So it's sort of like borrowing energy against the fatigue

that you will inevitably feel.

Now this actually has a very important

socioeconomical relevance.

Before caffeine was regularly consumed by human beings,

we were really slaves to the light/dark cycle.

And this was especially true before the presence

of artificial lighting.

But even before the advent of artificial lighting,

humans were largely constrained to the outside light/dark

cycle.

We need to be active during the day and working during the day,

and we need to be asleep at night.

Caffeine allows us to divorce ourselves

from that circadian cycle.

Circadian just means about 24 hour.

Caffeine allows us to do that at least somewhat by way

of increasing our alertness.

That is, spiking our alertness at various times

throughout the day and even at night.

This is how we can have shift workers, for instance,

that can sleep during the day and then drink

a strong cup of coffee at 8:00 PM

and then work into the night.

That ability completely transformed our society.

Now, of course, the healthiest schedule-- and we

know this with certainty.

The healthiest schedule for brain and body

is going to be alert during the daytime and asleep at night.

There's no question about that.

Shift workers run into all sorts of health problems.

And thank you shift workers for doing the important work

that you do.

We need you.

Air traffic controllers, paramedics, firefighters,

police officers, et cetera.

But we know that there are serious health consequences,

negative health consequences, that is, for shift workers.

But for most people out there, about 95% of people

follow a typical schedule.

They're awake during the day and asleep at night.

And yet it used to be before the advent

of caffeine-containing beverages that, if you were

sleepy in the afternoon, you either

had to take a nap or battle that sleepiness,

that your activity rhythms and your sleep rhythms were

governed by these circadian changes in availability

of sunlight and when you slept.

And you just didn't have the ability

to ingest a beverage that would increase

your levels of alertness because you block adenosine.

So this is important to understand

that, nowadays, we certainly live

in a time in which we use--

in fact, 90% or more of adults and half or more

of adolescents and teenagers use caffeine

as a way to negotiate with, to borrow

against this natural pattern of adenosine making us sleepy.

But again, you're just offsetting

the effects of sleepiness that adenosine causes.

You can't eliminate the adenosine entirely.

The important point is that adenosine

as a pro-sleep molecule is a nonnegotiable aspect

of your biology.

In fact, it's so nonnegotiable that, every 24 hours, you

are going to release adenosine, and you're

going to release adenosine in direct proportion to how long

you've been awake.

So the longer you've been awake, the more

adenosine circulating in your system.

There are really only a handful of ways to completely clear out

adenosine.

The major one being to get sleep.

The other is to take a short nap, which, of course, is

sleep, but it's shallow sleep.

Or non-sleep deep rest, so-called NSDR,

has been shown to reduce levels of adenosine.

And there are certain things such as viewing morning

sunlight, which because of its effects on cortisol,

can quote unquote, "clear out adenosine."

We'll talk about this in more detail in a few minutes.

And there's also evidence that certain forms of exercise,

provided that it's brief and intense,

can also reduce adenosine, not just block its effects.

Now that we've talked about some of the incredible mechanisms

by which caffeine changes our experience of life,

increases alertness and mood, et cetera,

I want to talk about the use of caffeine as a tool.

Now caffeine is a very potent and useful tool

for enhancing mental health, physical health,

and performance.

But there are certain considerations

one has to keep in mind, in particular, dose.

Now, first off, not everybody will

respond to the same dose of caffeine the same way,

but we can reliably say that your body weight is

a good measure by which you can estimate

what a healthy, useful dose of caffeine would be.

So for most people, ingesting 1 to 3 milligrams

of caffeine per kilogram of body weight

is going to be the range in which caffeine

can have positive effects without making us feel overly

anxious and give us that feeling that we're jumping out

of our skin and turn the otherwise

positive experience of caffeine into an aversive one.

For those of you that aren't familiar with thinking in terms

of kilograms and normally think in pounds,

I'll just quickly give you some general estimations

that, for instance, 100 kilograms equals 220 pounds.

So for me, I weigh 100 kilograms.

That means that 1 to 3 milligrams--

again, milligrams, thousandth of a gram.

1 to 3 milligrams of caffeine per kilogram of body weight

would mean for me.

I could safely ingest 100 to 300 milligrams of caffeine

in a single dose, in a single drink,

if that's the way I'm consuming it,

or pill form if that's the way that I'm consuming it.

And it's very likely that that will be a tolerable dose.

However, if you are not somebody that's

accustomed to drinking caffeine on a regular basis,

I suggest you start on the lower end of that 1 to 3

milligrams per kilogram of body weight range.

So for instance, if you're somebody

who weighs 50 kilograms, that's approximately 110 pounds.

And you would be pretty comfortable

ingesting somewhere between 50 and 150 milligrams of caffeine.

So what I recommend is that people who are considering

using caffeine as a tool or who are already ingesting caffeine,

start to think about the dosage of caffeine

that you are ingesting or plan to ingest

and the timing in which you ingest that caffeine

relative to certain tasks throughout your day,

your waking, and your sleep.

And we'll talk about that in just a moment.

But the first step for you is to figure out

how much you weigh in kilograms and then

to go to that number of 1 to 3 milligrams of caffeine

per kilogram of body weight.

And that's a good range in which you

might want to explore the use of caffeine

in a single application, meaning a single dose.

Now, I do realize that some people out there are

drinking coffee all day long or having coffee in the morning

and again in the afternoon.

What I'm referring to here is the ingestion of caffeine

in a single bout, right?

1 cup of coffee or 2 cups of coffee, for instance,

to achieve that 100 to 300 milligram

range if that's what's appropriate for your body

weight.

But to avoid any confusion, when I talk about dosage

of caffeine, what I'm really talking about

is not the total amount of caffeine ingested per day.

I'm talking about the total amount

of caffeine ingested in one sitting or setting, that is.

And if you're somebody who's drinking caffeine multiple

times throughout the day, you can imagine-- for instance,

let's say the appropriate dose for you

in order to get an enhancement in mental performance

or physical performance is 200 milligrams.

And you are somebody who's doing some work in the morning,

and you want to have that lift in the morning

to be able to focus better.

And you're doing some physical exercise in the afternoon

or vice versa that you would ingest 200 milligrams

of caffeine at two separate times per day

separated by about four hours.

Now you don't have to separate them.

You could put them two hours apart, for instance.

But we'll talk about half-life of caffeine and so forth.

Just keep in mind that, if you're ingesting 200 milligrams

of caffeine and that's the appropriate dose for you

based on your body weight and then you

are ingesting another 200 milligrams of caffeine an hour

later, you are effectively ingesting approximately 400

milligrams of caffeine, which is going

to start exceeding the dose in which you can normally

tolerate without feeling anxious and jittery.

With all of that said, there is a range

of tolerance for caffeine that's based on two things.

One is a preexisting disposition that is whether or not

your genetics and nervous system and the backdrop of your life,

how much stress you're experiencing

tends to make you feel more anxious and alert and jittery

before you ingest any caffeine.

And the other is how so-called caffeine-adapted you are.

We often hear about tolerance.

Tolerance means something very specific.

It's the ability to ingest more and more of something

with a plateau that is a no increase or an actual reduction

in the effectiveness of that thing.

But here we're not really talking about tolerance

to caffeine.

What we're talking about is being caffeine-adapted.

A simple way to understand whether or not

your caffeine-adapted or not is that, if you drink caffeine

and it tends to increase your heart rate

and make you feel more alert and a bit more anxious,

then chances are you are not caffeine-adapted,

provided the amount of caffeine is within the healthy range

for you, that is, the ranges we talked about a moment ago.

However, here's somebody who drinks caffeine

and you actually feel alert and relaxed,

chances are you are caffeine-adapted.

And so at various times during today's episode,

I'll talk about people who are caffeine-adapted

and people who are not caffeine-adapted.

We'll talk about the use of caffeine every other day.

I know a few habitual caffeine drinkers including myself,

just the simple mention of that probably sounds aversive.

But there is actually great utility

to using caffeine every other day as opposed to every day.

But just keep in mind that some people

will drink caffeine and not get much of a lift from it at all.

Other people will drink caffeine,

and they will feel extremely anxious even at dosages

far lower than that 1 to 3 milligrams per kilogram

of body weight range that I described a moment ago.

So you have to take into account individual differences.

That said, 1 to 3 milligrams of caffeine per kilogram of body

weight for a given sitting.

For your morning coffee or your morning yerba maté tea is

a good range from which to start.

And I do encourage you to go online and look up

the various beverages and foods that you might be

eating that contain caffeine.

For instance, some people are surprised to discover

that the coffee that they get from some of the more standard

popular vendors out there, the small coffee

or the medium coffee, for instance,

can contain as much as 400 to 600 milligrams of caffeine.

And the large coffee that is often

sold at those commercial vendors can

contain as much as 1 gram, 1,000 milligrams, of caffeine.

Now you may be adapted to that such

that it doesn't make you feel anxious,

but if you wonder why you feel irritable

and you get a headache when you don't

get that caffeine or that amount of caffeine

at precisely the time that you're used to getting it

each day, that's because you are consuming

quite large quantities of caffeine on a regular basis.

So I do recommend whether or not you drink soda or coffee or tea

that you figure out the source of that.

OK, so figure out what vendor you purchase it

from, what kind of coffee, and go online and spend

a little bit of time because the information is

out there to discover what levels of caffeine

you're actually ingesting.

Now if you happen to be ingesting more than 1

to 3 milligrams per kilogram of body weight of caffeine,

that's not necessarily bad.

However, you do want to be careful about ingesting

very high levels of caffeine over long periods of time

in your life because there can be issues that start to arise.

In particular, a bias towards higher levels

of anxiety and depletion of certain electrolytes.

Because caffeine is a diuretic can

cause you to lose sodium and other things of that sort.

And also just from simply a dependent standpoint,

it does appear that if you ingest high levels of caffeine

that is exceeding the dosages that normally you

could get away with and get just as

much mental-enhancing and physical-enhancing benefits

that you can cause some disruption

to the microvasculature.

You can bias yourself towards headaches, anxiety attacks,

and you can become actually quite irritable

when you're not getting those higher levels of caffeine.

So I do encourage you to figure out

not just what an appropriate caffeine dosage would

be for you but also how much caffeine

you might already be ingesting.

The first tool I'd like to talk about

is one that I've mentioned before

on this podcast several times.

And it's something that if you haven't heard of

will be very useful to you.

And if you have heard this tool before,

I'm going to add some additional features

to the description of this tool that

should make this worthwhile for you as well.

And that is to delay your caffeine intake

to 90 to 120 minutes after waking up on most days.

And I'll be very clear as to days

in which you might want to ingest caffeine more

closely to when you wake up.

Why would you want to delay your caffeine intake to 90

to 120 minutes after waking?

The answer to that is very simple.

Many people wake up in the morning.

They drink caffeine within 10, 20, 30, sometimes

within 2 minutes of waking.

And they feel more alert naturally.

That makes sense because of the effects of caffeine

in blocking the effects of adenosine

that I talked about earlier and its effects

on other neurotransmitter systems.

But then what they find is that, in the early afternoon,

in particular, after lunch, they experience a dramatic dip

in their overall levels of energy, the so-called afternoon

crash.

And in most cases, the way they respond to that

is to ingest more caffeine, which

indeed can increase their levels of mood and alertness.

However, as we'll soon talk about,

there is a problem with ingesting caffeine

in the afternoon if it falls within 8 or 10

or dare I even say 12 hours of going to sleep.

And that is, the caffeine ingested in the afternoon--

for most everybody, let's say for 95-plus percent of people--

disrupts the architecture and quality

of their nighttime sleep.

And I should say that it doesn't necessarily

impact their ability to fall asleep and maybe even sleep

through the night but that the depth and quality of that sleep

is disrupted by consuming caffeine in the afternoon.

A little bit later, I'll talk about how

you can offset some of those negative effects

if you absolutely require caffeine in the afternoon.

But there's a huge advantage to restricting your caffeine

intake to the early part of your day

but not consuming caffeine within the first 90

to 120 minutes after waking.

In fact, many people find that if they delay their caffeine

intake to 90 to 120 minutes after waking up

that they feel more alert in the morning,

and they completely avoid that afternoon crash.

Now that said, many people, including myself,

do need a short nap or non-sleep deep rest

or other form of relaxation for 10 to 30 minutes

in the afternoon.

That is natural and healthy.

I'm not referring to the need for that

when I refer to the so-called afternoon crash.

What I'm talking about in the afternoon crash

is a inability to recover energy and focus and a need

to consume more caffeine just to make it through the afternoon.

By delaying caffeine intake to 90 to 120 minutes after waking,

there are a couple of things that are accomplished.

First of all, you offset that afternoon crash.

And this is an effect that many people experience

the very first time they start delaying their caffeine

intake to 90 to 120 minutes after waking.

And the reason this works so well is the following.

As I mentioned earlier, adenosine

is a molecule that builds up the longer that we are awake.

It is a molecule that is reduced or cleared

from our system by sleep.

So when we emerge from sleep regardless

of how long we've slept, our adenosine levels

are lower than they were when we went

to sleep the previous night.

If you slept well enough and long enough,

those adenosine levels can be very, very low,

but they are never completely zero.

When you wake up in the morning, even

if you're one of these people that springs out of bed

and is ready to attack the day-- and here I'm certainly

not describing myself.

I'm not one of those people.

I tend to wake fairly slowly.

But if you're one of those spring up and attack the day

or you're one of the people who moves

more slowly into your day, regardless, there's

still some residual adenosine in your system.

And this is particularly the case

if you did not get enough sleep or enough depth of sleep

the night before.

The correct ratio is a slow-wave sleep and rapid eye movement

sleep.

And for those of you interested in optimizing sleep,

I'll just refer you to our master your sleep episode

of the Huberman Lab podcast, the perfect your sleep episode

of the Huberman Lab podcast.

And we have a tool kit for sleep all of which are available,

zero cost, time-stamped, et cetera at hubermanlab.com.

You wake up in the morning.

And your adenosine levels are low, but they're not zero.

And if you didn't sleep that well or deeply enough the night

before, you're going to have more adenosine in your system.

You might think the logical thing

to do is therefore to drink caffeine

and to block the adenosine that's there.

But what happens if you do that is

there's an accumulation, a sort of glut of adenosine

that hangs around.

And then in the afternoon, when the effects of that caffeine

start to wear off, you will experience

the so-called afternoon crash.

As I mentioned earlier, there is a way

to clear out the adenosine that's present when you wake up

in the morning and to clear it out essentially

completely without just blocking its receptors

and letting it accumulate or hang around.

And the way to do that is to deliberately spike

your cortisol.

Now, many of you have heard of cortisol, the so-called stress

hormone, as a bad thing.

And indeed, chronically elevated cortisol is a bad thing.

It depletes your immune system.

It's bad for psychosocial effects.

It tends to make us feel anxious and on and on.

But cortisol itself is not bad.

Cortisol is wonderful.

Cortisol enhances the efficiency of the immune system.

It makes us alert and focused.

It stimulates our metabolism.

It does a huge number of positive things, provided

that it is released in a circadian fashion.

That is, at the appropriate times

every 24 hours and that it tends to peak very close to waking.

In fact, one of the reasons you wake up in the morning,

assuming that you weren't woken up by some noise

or sleeping in an environment that's too warm, et cetera,

is that your cortisol levels start to rise.

And shortly after waking, your cortisol levels

will start to reach their peak.

And when I refer to a cortisol pulse,

that's just biology nerd speak for a rise

and peak in cortisol.

You want that cortisol pulse to occur early in the day close

to waking, and you want that for a couple of reasons.

First of all, if you don't restrict that cortisol pulse

to early in the day, it will tend

to bleed into the later parts of the day.

And actually, a late shifted cortisol peak

is one of the hallmark signatures

of depression, low-level depression,

and serious depression.

And it can start to disrupt sleep

and certainly can disrupt mood metabolism

and your immune system.

So you want that cortisol peak early in the day.

How do you ensure that that happens?

Well, you wake up in the morning.

And whether or not you're a bounce-out-of-bed type

or you're more groggy, you kind of wade slowly into the day

type like I am, you wake up, and you don't ingest caffeine.

Fine and, in fact, beneficial to hydrate

with water and electrolytes.

Terrific.

In fact, I would say necessary to get

bright light in your eyes ideally from sunlight.

I've talked about this many, many times

before on the podcast.

If you wake up before the sun comes out,

then turn on bright artificial lights.

But then certainly once the sun is out and even on cloudy days,

in fact, especially on cloudy days, get outside for anywhere

from 5 to 20, maybe even 30 minutes.

Do some work outside, take your breakfast outside

if you're a breakfast eater.

Get something done outside even if it's just to get outside

and get bright light in your eyes.

Why?

Well, because it's been shown in studies

on humans that getting bright light in your eyes

in the first hour after waking or as soon as possible

after waking increases the peak of that cortisol pulse

by 50%, 5-0.

And that cortisol pulse, yes, increases mood, yes, increases

alertness, but it does one other very important thing,

which is that, through an indirect pathway,

it can clear out any residual adenosine that

might be present in your system when you wake up

in the morning.

Again, this is going to be especially important for those

of you that are not getting as much sleep

or as much quality sleep as you would like.

It's going to be very important for you to get that morning

bright light ideally from sunlight,

get that cortisol peak going.

Other ways to increase that cortisol peak

would be to do some physical activity.

If you don't have time to do a full workout, well then,

getting some movement--

10 minutes of skipping rope or even

5 minutes of skipping rope or jumping jacks or walking

if that's all you have time for ideally while getting

the sunlight in your eyes.

But that's going to zero out the adenosine present

in your system.

If, however, you were to wake up and immediately

drink caffeine--

caffeine itself can stimulate the release

of cortisol a little bit more than it would otherwise

be present in your system.

But by blocking those adenosine receptors

and because of the indirect effects

of caffeine on the cortisol system,

you actually are reducing the clearance of adenosine

that would otherwise occur.

So I realize that's a mouthful.

Just to be very clear, if you wake up

and you ingest caffeine right away,

you're blocking the adenosine receptor,

but you're not clearing it out.

You're also preventing cortisol from having its normal increase

and rise such that it can directly clear out adenosine

because cortisol can clear out adenosine.

And that's what you want.

You want to be at maximum alertness

and focus in your morning and throughout your day.

And by delaying your caffeine to 90 to 120 minutes after waking,

you set up your system so that you get that morning cortisol

peak.

Ideally, a peak that's even greater because you're

getting your bright light viewing.

And then when you ingest your caffeine 90 to 120 minutes

after waking, not only will you be craving it just a little

bit, but you will be drinking that caffeine

on an already existing backdrop of increased alertness for two

reasons.

One is adenosine is zeroed out, and your cortisol peak

is higher.

And so now when you ingest caffeine,

you can actually ingest levels of caffeine

that are a little more reasonable that

almost with certainty are going to fall in this 1 to 3

milligrams per kilogram dosage and will allow you to feel

really alert and will carry that alertness well

into the afternoon hours without the need to drink more caffeine

and thereby will prevent you from drinking

caffeine and disrupting your nighttime sleep.

And, of course, by getting better nighttime sleep,

you're going to zero out your adenosine even more.

So what I'm describing here are essentially two tools.

I'm telling you to get morning sunlight and maybe

some exercise in conjunction with that

even if it's brief exercise.

But the main tool of delaying caffeine

90 to 120 minutes after waking has immediate effects,

but it also sets in motion a cascade or domino

falls that lead to better sleep and more wakefulness

the next night and the next day and so on and so forth.

Now I realize there are some people who just simply cannot

or will not delay their caffeine 90 to 120 minutes after waking

for whatever reason.

First off, let me say that, if you are somebody

who likes to wake up and do very intense exercise

within the first 90 minutes after waking, well,

in that case, it would be appropriate to ingest

your caffeine just prior to doing that exercise.

Not a problem.

Not a problem.

But you should expect that the combination of drinking

caffeine very shortly after waking plus exercising very

intensely shortly after waking will increase

the intensity of that early afternoon and afternoon fatigue

that you feel.

Now for some people, that's a great thing.

They can afford to take a nap or do non-sleep deep rest, step

away from work, and so forth.

In that case, I strongly encourage

you to do whatever it is that allows

you to get regular exercise because regular exercise is

going to be very beneficial.

In fact, we did an entire episode

called tool kit for fitness that describes a couple of different

but really one main structure that

allows you to get the appropriate amount

of resistance training and cardiovascular training

and flexibility training throughout the week.

I happen to follow that program, and it works very well.

And it does involve some of those workouts

to come very early in the morning shortly after waking.

And in those cases, I do ingest caffeine

just prior to those, so within 10, 20 minutes of waking.

However, on other days, I personally

delay my caffeine intake 90 to 120 minutes,

and I've done that to great benefit.

And most people, if not, all people that try that,

have reported the same.

I should mention that some people will find getting out

to that 90 minutes to be excruciatingly

difficult because they're so accustomed to ingesting

caffeine close to waking up.

In that case, maybe just push out your caffeine intake

by about 15 minutes each day until you

hit that 90 to 120-minute mark.

And that will make it much easier.

It might take you a week or so to get there.

But once you get there, you'll find it

to be quite easy to maintain.

The other thing is that, if you are somebody

who insists on drinking caffeine very shortly after waking,

I would encourage you to drink half of your caffeine then

and then the other half of your caffeine about an hour later.

That also will help offset some of the afternoon crash

for reasons related to the so-called kinetics of caffeine.

Caffeine has a quarter life of about 12 hours.

That means that if you were to ingest a cup of coffee

at let's say 8:00 AM--

and let's say 100 milligram coffee

just for sake of simplicity, that about 25% of that caffeine

action--

we wouldn't really say 25 milligrams, but about 25%

of that caffeine action will still

be present at 8:00 PM that night,

which is pretty remarkable.

So there's a long arc of caffeine effects,

and this is why it can impede sleep if we

take caffeine in the afternoon.

But again, if you're somebody who wakes up

and you really need caffeine right away

and you refuse to do this 90 to 120-minute delay thing

that I'm talking about, well then, in that case,

I would drink half of your caffeine upon waking

and then a little bit more or the other half about an hour

later.

And that will extend the arc of that caffeine effects

such that you don't need it again in the afternoon

because you won't experience the afternoon crash.

Because of the way caffeine works,

I should mention that, if you ingest caffeine

on an empty stomach, it will have a more potent stimulant

effect.

That will also tend to increase the level of jitteriness

that caffeine can produce.

Later, I'll talk about ways to offset that jitteriness,

but I'll just tell you one tool now.

Many people opt to take 100 milligrams of theanine,

T-H-E-A-N-I-N-E, theanine, as a way to offset some of that

jitteriness.

Theanine will reduce the jitteriness

of caffeine, which is why many energy drink

manufacturers and even some coffee manufacturers

are now putting theanine in energy drinks

and in ground coffee because, no surprise,

it allows people to consume more of that beverage

and thereby purchase more of that beverage, which

is what these vendors want without feeling overly

anxious and jittery.

So you can take pill form theanine

if you want with your caffeine.

I don't tend to do that.

Rather, I control the total dosage of my caffeine.

I do tend to consume caffeine on an empty stomach

because I do restrict my caffeine intake

to the early part of the day.

And I generally eat my first meal somewhere around 11:00 AM,

and then I generally my last meal some time around 8:00

PM or so.

Those are averages.

I would say plus or minus an hour.

And that's not because I'm religiously

following any kind of time-restricted feeding.

It's just that tends to work best

with my schedule and my appetite.

But again, that's a general theme.

There are days in which I wake up and I'm very hungry,

and I might ingest something, small snack or something.

Or if I'm meeting somebody for breakfast,

sometimes I'll have breakfast.

Sometimes I won't.

And so on and so forth.

The point is that you can get away

with drinking less caffeine to get the stimulant effect if you

do it on an empty stomach.

And if you're somebody who likes to exercise

on an empty stomach--

and I'm one of those people--

well then, ingesting caffeine just prior to exercise

can be a fantastic tool.

A little bit later, we'll talk about some

of the physical performance-enhancing effects

of caffeine.

But I'll just briefly jump to a point about that

as we relate to morning exercise.

If you are somebody who regularly ingests caffeine--

and we can define regularly by, if you've

ingested caffeine every day for the last two weeks,

you're a regular consumer of caffeine.

Whereas if you're somebody who only ingests caffeine

somewhere between two and four times per week, well then,

you are not a regular consumer of caffeine.

You're an intermittent user of caffeine.

Well, if you're somebody who's a regular user of caffeine,

the performance-enhancing effects of caffeine are going

to be most dramatic if you take two or three days off from

drinking caffeine, which to my mind as a--

I don't want to call myself a caffeine addict

but a regular caffeine user.

That's a horrible notion to me, it is an aversive notion,

because I do like the effects of caffeine so much.

But if you really want to see the maximum

performance-enhancing effects of caffeine,

you will do either one of two things.

You will either abstain from caffeine

for a few days or three days prior to ingesting caffeine,

or you will use caffeine on an empty stomach.

It's very clear that caffeine on an empty stomach

enhances both the mental and physical enhancing

effects of caffeine.

And, of course, all of that has to be stated

on the backdrop of consideration that you're very, very hungry,

it can be make it hard to concentrate

and so on and so forth.

So I'm not encouraging people to starve themselves by any means.

Certainly, don't do that.

But if you want to maximize the performance-enhancing effects

of caffeine, you will consume it on an empty stomach.

And then as a final point to that, caffeine is a diuretic.

It causes us to lose fluid and, along with that fluid,

to excrete sodium because of the effects of caffeine

on various processes within the kidney.

So one thing that works very well to maintain mood

and alertness longer given a certain amount of caffeine

intake and to avoid the jitteriness

and what can sometimes feel like a crash or low blood sugar

feeling or even blurry vision is to make sure

that you consume at least an equal volume of water

with your caffeine.

And ideally, that water would contain

maybe a small pinch of salt or some sort

of electrolyte drink--

or powder, rather.

For me, I use element.

Full disclosure, they are a podcast affiliate and sponsor.

But you don't need to do that.

You could simply just have a glass of water alongside

your coffee or espresso or your yerba maté and just put a small

pinch of sea salt in that or evem just playing table salt.

And that will help offset some of the jitteriness of caffeine.

A lot of people think that, when they ingest caffeine,

they get the jitteriness and crash because their blood

sugar is low.

And while that can be the case, oftentimes, it's

simply because of the excretion of sodium

that's occurred when they've ingested caffeine.

So I encourage you to hydrate well

and to hydrate with something that contains

a little bit of sodium.

Obviously, not so much that increases hypertension

or something of that sort but a small amount of sodium

or an electrolyte drink like Element.

And there are other electrolyte drinks

out there that can accomplish the same, of course.

Just a couple of quick notes about

theanine because there are a growing number of products

out there that contain theanine.

And there's certainly a growing number of people out there

who are using theanine for the effect that I described before,

which is to offset some of the jitteriness associated

with caffeine-containing beverages or foods.

And, of course, I should mention that I've

talked about the effects of theanine

on sleep at that sleep tool kit that you

can find as a free download.

You don't even have to sign up for.

Anything you just download it from hubermanlab.com.

Go to the menu, go to a newsletter.

You'll see the tool kit for sleep.

You'll see that the so-called sleep stack

that I use and recommend includes magnesium 3 and 8,

something called apigenin and theanine,

although that sleep stack is designed

to be taken 30 to 60 minutes prior to sleep.

And I make the point there, and I'll

make it again here that ingesting theanine prior

to sleep is not a good idea if you are somebody

who tends to have very vivid dreams, night terrors, or night

walk--

sleepwalking, excuse me, et cetera.

In that case, eliminate theanine from the sleep stack.. .

However, a number of people are using theanine,

and products are using theanine to offset jitteriness

from caffeine-containing products

during the daytime, daytime consumption, that is.

A couple of notes about theanine-- theanine

is something that is present in green tea, right?

It's now been created as a supplement.

It's what's called a nonprotein amino acid.

So while there are amino acids and proteins,

there are, of course, amino acids and nonproteins.

And theanine is one such nonprotein amino acid.

Theanine tends to stimulate the so-called glutamate and

glutamine pathway.

It's actually very similar to glutamate and glutamine,

and it has a lot of effects on a lot of different aspects

of the nervous system.

But the general effect of theanine

is to compete for the receptors for certain neurotransmitters.

And the neurotransmitters I'm referring to

are all excitatory neurotransmitters,

things like glutamate.

And they govern a tremendous amount of our daily thinking

and action and feeling, et cetera,

because they're present at so many connections

between neurons in the brain.

Theanine competes for the receptors for glutamate

and tends to reduce our overall levels of alertness.

So really, when people take theanine along

with caffeine, what they're doing

is they're really taking a slight--

I don't want to call it depressant to the point

where it misleads people and makes people think that it

will make you depressed.

The word is a little bit misleading.

But it tends to reduce or blunt some

of the more excitatory pro-alertness actions

of neurons in the brain.

So when you take it alongside caffeine,

tends to, quote unquote, "even things out a bit."

I should mention that the dosages of theanine

that are effective for offsetting

the jitteriness of caffeine is 200 to 400 milligrams,

and the studies that I was able to find

showed that essentially up to 900 milligrams per day

can be safe.

But that's a very high dosage of theanine.

In fact, so much so that it might increase

sleepiness to the point where it wouldn't feel good.

There are also some positive effects

of daytime consumption of theanine

that are independent of reducing the jitteriness of caffeine.

For instance, there's a study demonstrating

that 17 days of ingesting theanine at these 200 to 400

milligram dosage at one to three times per day

can reduce depression and anxiety.

There are also some good data out there showing

that theanine can have positive effects on endothelial cells--

so blood vessels, capillaries, and so on--

and increase some of the function of blood vessels,

allowing them to pass more blood through them

and give them a little bit more elasticity, if you will.

So theanine has certain pro-sleep effects

if it's taken prior to sleep.

It can enhance the quality, depth, and duration of sleep.

Again, if you're a sleepwalker or somebody who

has extremely vivid dreams from which you wake up

in the middle of the night, probably best

to leave out theanine or maybe reduce the dosage down

to 100 milligrams.

And if that's still too much, then eliminate it completely.

But theanine can be terrific for enhancing quality, depth,

and duration of sleep.

It can also reduce the jitteriness

associated with caffeine-containing beverages

and foods.

And it has certain antidepressant

and pro-endothelial effects.

That is, it can offset depression.

It can offset anxiety, although those are minor effects,

subtle effects.

And it has been shown to improve endothelial cell.

That is, vessel and capillary function and structure

in ways that can be beneficial for both brain and body.

Now one final point about theanine

that's worth paying attention to is

that the kinetics of theanine are

such that you don't need to take theanine every time you ingest

a caffeinated beverage.

When we ingest caffeine, the peak effects of caffeine

occur about 30 minutes after we drink it.

And there, I'm assuming one takes it all at once.

And this is a key point that we'll come back to later rather

than sipping your coffee slowly over a couple of hours

or an hour.

If you drink all 200 or 300 milligrams of caffeine

in your coffee or 600 milligrams of your coffee

if you're getting one of those commercial coffees

and you take theanine along with it,

theanine will block some of the jitteriness

and anxiety-inducing effects of caffeine

that can occur for much longer than the effects that

caffeine lasts.

So the peak in theanine occurs about an hour after ingestion.

I suppose if you want to get really fancy

and really dial in the kinetics, you

could ingest theanine about half hour

before you ingest your caffeine.

But I think that's getting a little bit excessive in terms

of controlling your microenvironment, if you will.

I think it would be perfectly fine to take a 100 to 200

milligram capsule of theanine along with your coffee or tea

or so forth and just realize that if you drink more caffeine

or you extend your caffeine intake over several hours

that you don't necessarily have to take theanine repeated

times throughout the day.

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Let's talk for a moment about when to avoid caffeine.

And in the same stroke, let's also talk about some

of the myths around caffeine.

For instance, one of the major myths around caffeine

is that it can increase osteoporosis.

It turns out that, while there is a relationship, of course,

between calcium and osteoporosis--

that is reductions in bone density.

And it is the case that caffeine can extract calcium

from certain tissues.

The large scale studies that are out there essentially

prove that, if people are ingesting enough calcium

through their diet, which most everybody is-- although

certainly, there are some people that

need to supplement calcium or make it a point to consume

more calcium-containing foods.

But assuming that you are getting

adequate levels of calcium, there

is no direct relationship between caffeine intake

and osteoporosis, at least not that I'm aware of.

I know this was debated for a number of years

in the literature, but the literature

seems to have arrived at a general consensus

now that caffeine itself is not going to create or exacerbate

osteoporosis, provided people are getting enough calcium

through their diet.

That is, through foods, through supplementation, or both.

Some of the other myths around caffeine

are that, for instance, caffeine will reduce testosterone levels

or will reduce estrogen levels.

Other myths out there are in exact opposite

to that, that caffeine will increase testosterone levels,

in particular, free testosterone levels.

There have been some large scale studies addressing the hormone

effects of caffeine.

They are a little bit difficult to do.

I should just mention that caveat.

And the reason they are difficult to do

is because 90% of adults are consuming caffeine.

And therefore, you can imagine it's

very hard to find a control group to compare the caffeine

consumers to.

In particular, a control group that's

well controlled for other things like lifestyle, diet, exercise,

et cetera.

However, when one controls as well as one can

for all the various factors that could impact hormones, what one

discovers is that caffeine intake, at least at the dosages

we talked about earlier, 1 two 3 milligrams per kilogram

of body weight or even up to double that,

that there are no consistent increases or reductions

in testosterone or estrogen in men or women

that can be directly attributed to the caffeine intake.

And I say directly attributed because in these association

studies, one always has to wonder,

for instance, if because people are ingesting more caffeine,

they have more energy and therefore exercising more.

And exercise is known to have effects

on testosterone, estrogen, and other hormones,

whether or not the effects of caffeine on those hormones

is indirect and so on and so forth.

And this all just underscores the challenges

of doing studies on humans in the wild

in their natural habitat of living as opposed

to an acute study as it's called to bring someone

into the laboratory and studying them just

for those hours or moments.

With all that said, there does appear to be a relationship

between caffeine intake and so-called sex hormone binding

globulin, which is a protein present in the body of both men

and women that binds to the sex steroid hormones--

testosterone and estrogen-- and prevents them

from being in their free or active form.

It has been shown that ingestion of caffeine--

even in the sorts of dosage ranges that are considered safe

and that we've been discussing-- can increase sex hormone

binding globulin such that it can slightly

reduce overall levels of free testosterone

and free estradiol in women.

Now those effects are relatively minor, but they do exist.

If any of you are interested in reading further

into the effects of caffeine on hormones,

I'll just refer you to a couple of studies.

We will link to this in the show note caption.

The title of the study is "Consumption

of caffeinated beverages and serum concentrations of sex

steroid hormones in US men."

And within this study, there is a reference

to a equally sized empowered study done

on women, both of which converged

on the same conclusion, by examining more than a thousand.

So in this case, 1,410 men or more than a thousand women,

that there are increases in sex hormone binding globulin

associated with increased intake of coffee, in particular.

But they were able to narrow that down specifically

to ingestion of caffeine.

So it's not coffee per se that's causing the increase in sex

hormone binding globulin.

It's actually caffeine itself.

So again, the increases in sex hormone binding globulin

were not so significant that, at least to my mind,

they seem like a concern, although I

think that it is worth noting that if you're going to consume

caffeine that you probably want to consume caffeine

in a way that is in dosages and with the sort of timing that

will allow you to get away with ingesting caffeine

but not to excess, so to derive the benefits of caffeine

without for instance driving up sex hormone binding globulin

too far.

Now why would that be a good idea?

Why would you want to make sure that you have enough free

testosterone and free estrogen?

Well, some of that is related to the acute effects

of those hormones in terms of well-being and libido

and strength and mood, et cetera, but some of those

also relates to the longer term effects of sex steroid

hormones.

Many people don't realize this, but the sex

steroid hormones operate on the receptors

at the surface of cells to have immediate effects.

But they also can enter cells and actually

go into the nucleus of cells where the DNA of those cells

are contained and control gene expression in those cells.

So the sex steroid hormones, testosterone and estrogen,

are controlling a lot of different cellular functions

over long periods of time.

So blunting their action over long periods of time

is probably not a great idea.

But again, at the dosages of caffeine

that we're talking about today, 1 to 3 milligrams

per kilogram of body weight, unlikely

that the increases in sex hormone binding globulin

that one experiences from that are going to be detrimental.

And certainly, the positive effects

of caffeine that one experiences in terms of mental performance

and physical performance and the fact

that it increases energy to do the sorts of things

like exercise that we know can profoundly

improve hormone profiles, twofold

or threefold improvement in hormone profiles.

In that case, it seems that ingesting caffeine is overall

a good thing, provided it's not in excess.

That also makes this the appropriate time

to mention one of the more impressive effects of caffeine,

which is on overall levels of mood and mental health.

There are several studies on this,

but the one that I'm particularly fond of

was published in 2019 in Psychiatry Research.

And the title of the paper is "Inverse association

between caffeine intake and depressive symptoms

in US adults."

And these are data from the National Health and Nutrition

Examination Survey.

And the basic takeaway is that, while, of course,

there are a ton of different factors

that are going to relate to whether or not

people are depressed or not, life circumstances,

genetics, and so on, that--

and here I'm quoting from the study.

"Caffeine's psychostimulant properties--

that just means the ability to make

us feel more alert and positive--

appeared to protect against depressive symptoms."

And, of course, they acknowledge that additional studies are

needed, but this is just one of several studies pointing

to the fact that people who regularly ingest caffeine

in the appropriate dosages do seem

to enjoy an antidepressive effect overall.

I wouldn't want anyone to consider caffeine

a treatment for severe depression

or at least not alone a treatment

for severe depression.

But provided the anxiety-inducing effects

of caffeine can be kept in check through use of theanine

or making sure that the dosage and the timing of caffeine

ingestion is correct, then caffeine overall

seems to be good for our mood and prevent depression

or at least keep depression at bay

when depression might otherwise surface or be more severe.

And, of course, there are the don'ts surrounding caffeine

intake as it relates to sleep.

And to put it very simply, sleep--

that is getting enough quality sleep

each night-- is the foundation.

It is the bedrock of mental health, physical health,

and performance.

Sleep and the power of sleep far exceeds any nootropic

you could ever take, any prescription drug

you could ever take, any health-promoting tool

for your immune system, your metabolism,

your mental function, your physical function you

could ever take.

Sleep is the bedrock.

I know a lot of people experience challenge

with sleep.

Nobody is perfect about sleep.

That's important to keep in mind.

I think a good goal is to get enough quality

sleep of sufficient duration 80% of the nights of your life

and then as much as possible to make sure that the remaining

20% of nights you are not getting enough

sleep for good reasons as opposed to hard reasons.

Good reasons would include raising children.

That's important.

After all, every species desires to make more of itself

and to preserve and extend the well-being of its young,

so child-rearing is a perfectly legitimate reason

to get a lack of sleep.

But you really want to strive to get quality sleep most nights

of your life, which means that, even if you're somebody who

can, quote unquote, "drink an espresso"

and then fall right asleep, that you avoid caffeine intake

in the 12 hours prior to sleep.

I realize not everyone will be able to do that.

And in fact, I sometimes violate that,

so I tend to go to sleep around 10:00 PM every night,

sometimes 11:00, occasionally 12:00 midnight,

but usually around 10:00 PM every night.

I confess that my last ingestion of caffeine

is not always 10:00 AM or prior to that,

so sometimes I will have caffeine up

until 11:00 AM or maybe noon.

And very, very rarely, I'll have an afternoon coffee or espresso

or noncalorie-containing soda or tea or something

that's of that sort.

But I really tried to restrict my caffeine intake

to the early part of my day that is before noon, given

that I go to sleep around 10:00 PM each night.

And I strongly encourage everyone out there

to try and limit their afternoon caffeine intake.

This is something that Dr. Matt Walker, who's an expert

sleep researcher out of University of California

Berkeley Psychology and neuroscience department there,

author of the incredible book Why We sleep.

He's been on this podcast, many other podcasts,

talking about the importance of sleep.

He will remind us, and I'll remind you now

that the quarter life of caffeine is 12 hours.

I mentioned this earlier, but I'm going to repeat it again.

And that means that, if you ingest caffeine at noon,

25% of its effects more or less, OK?

I'm using a broad stroke here to talk about quarter life.

25% of that is still going to be bioactive at midnight

that night, which will disrupt the early phase of your night,

the amount of slow-wave sleep, which then in turn

will disrupt the amount of rapid eye movement sleep, which will

disrupt your emotional processing

during the following day and so on and so forth.

None of this is to say that if you

have the occasional cup of coffee in the afternoon,

that it's going to completely demolish

your sleep/wake cycle forever.

But I really encourage people to avoid drinking caffeine

in the 12 hours prior to sleep.

And if you can't do that, within the 10 hours prior to sleep.

And if you can't do that, within the 8 hours prior to sleep.

So really try and limit your caffeine

intake in the 8 to 12 hours prior

to going to sleep at night.

And, of course, slow-wave sleep, aka deep sleep,

is the sleep that's associated with somewhat mundane dreams,

which makes it sound like it might not be that important.

But it's also the sleep that's associated with growth hormone

release, which is important for protein synthesis,

repair of all bodily tissues and metabolism.

And slow-wave sleep is also critically

attached to your immune system's ability

to clear out bacteria and viruses that might otherwise

infect your tissues.

Now I'd like to talk about caffeine and performance.

And that includes both mental performance

and physical performance.

Now I'd like to talk about caffeine

and its positive effects on performance

when used correctly.

And here we are referring to both mental performance

and physical performance.

The exploration of caffeine as a pro-performance tool

has been explored since the 1930s, at least

that's some of the earliest documented literature on this.

Although I have to imagine, given

that people have been using caffeine for much

longer than that, that long ago somebody realized that,

by ingesting a certain plant, that they

felt much more alertness and were

able to hunt and gather or do any number of different things

better and, as a consequence, decide

to consume more of that plant.

Now these days, we consume a lot of caffeine

in the form of coffee and tea mainly,

and some people consume it in the form of caffeine tablets

or energy drinks, et cetera.

Across the board, one finds that caffeine intake

at a level of 1 to 3 milligrams per kilogram of body weight

improves reaction time.

That is, it reduces the amount of time

to take a physical action or to answer a question correctly

with a verbal response.

It can also improve coordination.

It can also improve memory, although I

do want to mention that, whereas most studies of the effects

of caffeine on improving mental and physical performance

involve taking caffeine at 1 to 3 milligrams per kilogram

of body weight before the mental task or physical task,

there is also a pro-performance effect of caffeine on memory

if one takes caffeine after learning certain material

or I should say being exposed to certain material.

We'll come back to that in a few minutes.

If one examines reaction time, mood, alertness, focus,

and memory or the ability to call up

information from memory, or physical dexterity, power

output, endurance, and overall feelings of well-being

during exercise and exertion, caffeine

has been shown in numerous studies in both men and women

to improve all of those metrics significantly.

So this is all just to say that caffeine

is an incredible performance-enhancing tool.

Now, what's not obvious from the statement that caffeine is

a performance-enhancing tool across the board

and in men and women and in different contexts

is that the way in which caffeine is taken

is very important.

Because 90% or more of adults consume caffeine,

finding controls for studies of caffeine is really challenging.

That is, finding people who don't ingest caffeine

regularly is a very challenging task for the researcher.

And as a consequence, many of the studies

of caffeine on human beings involve

depriving regular caffeine users of caffeine

and then examining the effects of caffeine

given after a period of, say, 5 to 15 days of abstinence

in a person that is essentially experiencing mild withdrawal

symptoms because they haven't had the caffeine that they were

used to getting.

So this is an important point.

And it's a point that likely exacerbates

the observed pro-performance effects of caffeine.

Now all of that isn't necessarily a problem,

provided you keep it in mind.

And it actually points to a way in which

even if you're a regular caffeine user,

you can extract more of the benefits of caffeine.

The simplest way to do this, for instance,

is to look back to what we talked about earlier in terms

of the need to have most of your cortisol increase restricted

to the hour or hours just after waking in terms of mood

and alertness and performance.

One of the ways to increase the peak of that cortisol

early in the day is to consume caffeine shortly

after that peak occurs.

And this was really nicely demonstrated

in a study entitled caffeine stimulation

of cortisol secretion across the waking hours in relation

to caffeine intake levels.

We will provide a link to this study.

It's a somewhat complicated study

because they looked at a bunch of different times of day

for caffeine intake.

And I should mention, in this study,

they use this 300 milligrams per day or 600 milligrams per day.

So that's quite high, although for people of sufficient body

weight and who are accustomed to taking caffeine,

it's certainly not going to be in excess

of what a lot of people out there are taking.

But basically, what they observed was the following.

Cortisol responses to caffeine are reduced but not

eliminated in people who consume caffeine on a daily basis.

What this means is that, if you wake up--

as I recommended earlier, you avoid

drinking caffeine for the first 90 to 120 minutes after waking,

but you do get some sunlight or other bright light in your eyes

in that time, maybe even get some exercise

in that time, which would be even better--

and then you ingest caffeine, you will get a further increase

in cortisol, which, provided it's restricted

to the early part of the day, is a good thing overall for mood

and alertness.

So this is a simple performance-enhancing tool,

which is to stack caffeine on the tail

of that early cortisol peak.

I should also mention, however, that, in this study,

they had people do a five-day caffeine abstinence prior

to being tested with 300 milligrams or 600 milligrams

of caffeine.

So the simple tool to extract from this and other studies

like it is that, if you want to experience

the maximum alertness-promoting effects of caffeine

when you ingest it early in the day,

you would abstain from caffeine for five days

and then ingest caffeine 90 to 120 minutes after waking.

I would still hope that you were doing all the other things

that I described-- morning sunlight, exercise, et cetera--

correctly.

But regardless, it's very clear that a five-day abstinence

from caffeine however painful that might be

will increase the performance-enhancing effects

of caffeine when you take caffeine on that sixth day.

Now, I'm sure many of you out there are saying, why would

I ever want to abstain from caffeine for five days

in order to just get this six-day performance-enhancing

effect?

Well, there are a couple of reasons for doing that.

Perhaps you're planning to travel to a new time zone,

and you want to use caffeine as a stimulant

to stay up during the day in the new time zone.

That's a somewhat unusual case.

Others of you might be interested

in the pro-physical performance effects of caffeine.

We'll talk more about these in a little bit.

But you want to get the maximum strength

increase or the maximum endurance increase

from ingesting, in this case, 300 to 600 milligrams

of caffeine.

Well, in that case, abstaining from caffeine for five days

will greatly exacerbate the pro-performance effects

of caffeine when you take it on that sixth day,

although admittedly, those five days are

likely to be pretty painful if you're a regular caffeine user.

Another variation on this, however,

might be to have the amount of caffeine

that you ingest on a daily basis and then go back

to your regular level of caffeine intake on that

day in which you need the caffeine to really boost

your mood, energy, and performance.

Another reason why you might want to abstain from caffeine

or reduce your caffeine intake for a period of time

and then go back to your regular caffeine intake

is simply to identify how much of an effect caffeine

is really having on your overall level of daily functioning

and mood.

This was something that was actually

covered in beautiful detail in a book by Michael Pollan

all about caffeine.

It's available on Audible.

I really enjoyed that book.

It describes his experience with the decision

to completely abstain from caffeine

for a period of months, although I confess that after hearing

that book, what it basically made me want to do

is never quit drinking caffeine because it sounded

as if, at least my interpretation was, that

even after several weeks or months of abstaining

from caffeine, that he still fantasized

about the effects of caffeine.

But he did mention that, when returning to ingesting caffeine

after a period of long abstinence,

that it had almost a--

let's not call it a psychedelic property,

but it had such obvious effects on mood

and alertness and feelings of well-being

that it really highlighted for him the extent

to which caffeine normally was allowing him to just function

what he thought was normally.

So in other words, many of us don't even

really know what our normal basal level

of cognitive and physical functioning

is because we're ingesting caffeine

on such a regular basis.

I confess that, as much as I enjoyed that book

and as intriguing as his description of caffeine

abstinence and then the return to caffeine was,

I don't intend to ever find out personally.

Now a very good reason why you might

want to abstain from caffeine for a deliberate period of time

and then return to caffeine intake

is for its physical performance-enhancing effects.

And here we can look to a really interesting study.

The title of which is "Time course

of tolerance to the performance effects of caffeine."

And what I like about this study is that, while yes,

it does say that abstaining from caffeine

and then returning to caffeine intake

can enhance physical performance in a very specific way,

it also says that, if you take caffeine regularly,

you can still see the physical performance-enhancing effects

of caffeine.

Although they are not quite as robust as they would be had

you abstained from caffeine.

The design of the study is pretty straightforward.

They had people either ingest 3 milligrams

per kilogram of caffeine for 20 consecutive days.

Many people are already doing that, I realize,

but they had people do that or ensure

that they were doing that.

Or others ingested a placebo for 20 days,

so they abstained from caffeine without realizing it.

Then after that 20 days of either ingesting caffeine

or a placebo, their peak performance

was measured in terms of aerobic output.

But prior to that measurement, they had caffeine, OK?

So it's 20 days of caffeine and then a 21st day of caffeine

and then the physical task on that 21st day.

Or it's 20 days of abstinence from caffeine.

And then on day 21, you get caffeine,

and you get the same physical test.

And what they discovered was that the ingestion of caffeine

increased peak performance in this aerobic output

dramatically if people had abstained from caffeine.

But for people that had consumed caffeine all the way through up

until that day, it still was effective to ingest caffeine

on day 21 but not as effective as it would have been had

they abstained.

And in fact, the magnitude of what

they call ergogenic effect, which

is the pro-performance-enhancing effect of caffeine,

was higher on the first day than in subsequent days

when they allowed people to continue caffeine intake.

So the takeaway from this study is really straightforward.

If you want to get the maximum physical performance-enhancing

effects of caffeine, you abstain from caffeine for 20 days.

Then on day 21, when you're going

to do the physical thing, the task,

you ingest caffeine about 30 minutes to an hour

before you do that physical challenge.

Now 20 days of abstinence is going

to be rough for a lot of people.

I certainly don't want to sign up for this study.

In which case, you might want to do five days of abstinence

as we talked about before.

And then on day six is the day that you ingest caffeine and do

the physical task.

There are even some studies showing

that you can abstain from caffeine for just two days,

for just 48 hours.

And, in particular, if you are a regular user of caffeine,

this allows you to, on day three,

ingest caffeine at the dose that's appropriate for you

and do the physical, or I should mention mental performance task

and perform significantly better than those

that have been taking caffeine throughout the entire period

leading up to the challenge.

So you don't necessarily need to abstain for 20 days

in order to get the pro-performance effects

of caffeine on day 21.

You could do five days of abstinence prior or even

two days of abstinence prior.

Or if that's intolerable to you as it is in my mind,

to me, to just reduce your caffeine intake slightly

or even perhaps have it if you can tolerate that

in the week or two weeks or maybe even three

weeks preceding some physical or mental challenge.

Now again, this sort of implies that you're going up

against a marathon, or you're going up

against a series of long tests, maybe standardized tests

in one day.

There, I just really want to point out

that there is an abundant literature showing that people

perform best on mental tests if they are in the state

that they were when they studied for that material.

Now in college, I knew a number of people

who took this to the extreme, thinking that if they were

to study under the effects of alcohol,

that they would be best off consuming alcohol

prior to taking exams.

And it turns out to not be the case.

Here we're talking, in particular, about

psychostimulant effects of caffeine and other compounds.

So don't think that you can drink

or be under the influence of THC and then take--

when you study and then take an exam under the same influence

and do just as well as you would had you not ingested anything.

Please don't let that be the takeaway.

However, do let it be the takeaway

that caffeine's effects are made more

potent by a brief to not so brief period of abstinence

prior to taking a dosage of caffeine.

And then the final point to make is

that, if you are somebody who is not accustomed to drinking

caffeine, meaning you're hypersensitive to caffeine

or you don't regularly ingest caffeine, please

do not ingest caffeine on the day

of any important mental or physical challenge

or performance, because what you will find

is that because you are not caffeine-adapted,

you will experience changes in your thermal regulation,

in your levels of anxiety and jitteriness,

and your levels of focus that could

be very detrimental to mental or physical performance.

So you don't want to throw yourself in the deep end

by ingesting caffeine if you're not used to it.

And I should mention that for people

that are not accustomed to ingesting caffeine

or are very sensitive to caffeine.

Even 25 to 50 milligrams of caffeine in the amount

that's found in, for instance, a piece

of certain types of chocolate can actually cause anxiety.

So be careful there.

Here, I'm referring only to people that are accustomed

with caffeine intake.

So what I recommend is to explore the ergogenic effects

of caffeine during your training and then to make a decision

about what you can reasonably and reliably do

in terms of abstinence and then pulse with caffeine

on the day of the challenge.

I get a lot of questions as to whether or not

caffeine has different effects on the nervous system

and on performance in particular, depending on phases

of the menstrual cycle.

So I explored that in my research for this episode,

and I found two studies both of which

we will reference in the show note captions.

The first one is entitled "Caffeine consumption

and menstrual function."

So it's actually the relationship between caffeine

and menstrual function.

We will do an entire episode about the menstrual cycle

and menstrual function.

But the other one as it relates to performance

was published in 2020 in the European Journal of Nutrition,

which is "Ergogenic effects of caffeine

on peak aerobic cycling power during the menstrual cycle."

And the basic takeaway of this study is--

frankly, a very nice study, showed that quote, "Caffeine

increased peak aerobic cycling power in the early follicular,

preovulatory, and midluteal phases of the menstrual cycle."

Thus, the ingestion-- and again, here they

use 3 milligrams of caffeine per kilogram of body mass

might be considered an ergogenic aid for women

who are in the menstrual cycle during all three

phases of their cycle.

So keep that in mind, women--

for those of you that are regular users of caffeine

or you're using caffeine to enhance physical performance,

there does not seem to be any menstrual cycle phase-dependent

effects of caffeine on performance.

That is, caffeine seems to always increase

physical performance regardless of the phase

of the menstrual cycle you might happen to be in.

I'd like to touch on a little bit more of the use of caffeine

for enhancing mental performance.

Yes, it is the case that ingesting 1 to 3 milligrams

of caffeine per kilogram of body weight in the 30 minutes

or so prior to doing a memory task

or sitting down to doing some studying

or learning of any kind, physical or mental performance,

of any kind is beneficial for all the reasons we talked

about before, relate to dopamine and acetylcholine, et cetera.

But it turns out that it is also the case that

spiking one's adrenaline and other so-called

catecholamines-- so this would be dopamine, norepinephrine,

and epinephrine-- after a bout of learning

can greatly enhance memory for the information

that one was trying to learn.

That's right.

Spiking your adrenaline after learning

can greatly increase memory for the material

you're trying to learn.

In fact, this is a practice that dates back centuries and was

written about in a beautiful Annual Review of Neuroscience

on the biology of memory by James McGaugh, where he talks

about medieval practices of children

being taught information and then being thrown literally

into cold water to stimulate the release of adrenaline

and that increase in adrenaline.

While the mechanism wasn't completely understood,

it was understood that that sort of shock

to the system from the cold water

led to better memory and retention of the information

that these children had been exposed to.

And it turns out the exact same thing

is true for adults in the laboratory

or kids in the laboratory.

And here I'm not suggesting throwing anyone

into cold water.

If you want to get into cold water,

there's a reason we call it deliberate

cold exposure on the podcast is that it

should be deliberate and controlled by you, not

by somebody else.

And if it's controlled by somebody else,

that might be military screening or something.

But here we're talking about deliberately increasing

your levels of adrenaline and other catecholamines, dopamine,

norepinephrine, et cetera.

You can do that certainly by deliberate cold exposure

with a cold shower or getting in up to your neck

in cold water of any kind.

But the other way to do that is to spike your adrenaline

by ingesting 1 to 3 milligrams per kilogram of caffeine

after sitting down to try and learn some material I confess

that, more often than not, I use caffeine in the same way

that most people use it, which is OK.

I'm going to sit down.

I'm going to research information for a podcast

or assemble some information for a paper or grant,

and I want to focus.

So I will drink a cup of coffee at the beginning of that

and maybe even throughout that or a couple of yerba maté

at the beginning or throughout that.

Or I'll sip on one or both throughout trying to learn.

And that works quite well in terms

of maintaining focus and alertness and retention

of information, but it is indeed the case.

That is, the research supports the fact.

And I've experienced the fact that,

if I abstain from caffeine while I'm trying to learn something--

but then I drink caffeine immediately after.

Somewhat surprisingly to me but certainly in a way that's

consistent with the research literature, memory

for the information that I was focused on prior to ingesting

that caffeine is much greater.

And here I'm talking about as a personal anecdote,

but this is actually what the data point to both in animals

and in humans.

And if you think about it, it makes perfect sense

because the way that the memory systems of the brain

are organized is that we go through life experiencing

things.

We encounter surprises both good and bad.

We go through the motions of things both typical, mundane,

exciting, and novel, and not novel.

And then every once in a while, something

will happen that will spike our catecholamines.

Dopamine, typically if it's a positive surprise.

Adrenaline, which can be associated

with both positive surprise or positive events

and negative events or surprises.

And without fail, increases in the catecholamines

tend to lock in memories for things

that preceded the increase in those catecholamines.

Again, the catecholamines being dopamine, epinephrine,

and norepinephrine, sometimes all three in combination,

sometimes just two of those, sometimes just one of those,

depending on the experience.

So it makes perfect sense that using caffeine

at the end of a learning bout would