How to Breathe Correctly for Optimal Health, Mood, Learning & Performance | Huberman Lab Podcast

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 breathing.

Now, breathing is something that we are all

familiar with because, frankly, we are all doing it right now.

And we do it during our waking states and while we are asleep.

And most of us have probably heard that breathing

is essential to life.

We hear that we can survive without food for some period

of time, maybe even up to a month or more,

that we can't survive that long without water,

but we could survive a few days without water,

depending on how well hydrated we are when we go into that

water deprivation and the heat of the environment we happen

to be in, but that we cannot survive without breathing

for more than a few minutes and that if we cease to breathe,

that our brain and our bodily tissues will die.

And, in fact, that is true.

However, despite everybody's knowledge

that breathing is essential to life,

I don't think that most people realize

just how important how we breathe

is to our quality of life.

And that includes our mental health, our physical health,

and what we call performance, that

is, our ability to tap into skills,

either physical or cognitive, in ways that we would not

be able to otherwise if we are not breathing correctly.

So today, we are going to talk about what

it is to breathe correctly, both at rest, during sleep, in order

to reduce our levels of stress, in order to wake up

or to become more alert deliberately,

and many, many other things, including

how to stop hiccuping.

This is one of the most searched for topics on the internet.

Today, I will teach you the one method that

is actually linked to science.

No, it does not involve drinking a glass of water

backwards from the opposite side of the cup

or holding your breath in any kind of esoteric way.

It actually relates to the neural mechanisms, that is,

the brain to body connections that cause the hiccup.

Hiccup is a spasm of that neural circuit,

and I'll teach you how to turn off that neural circuit in one

try.

And that's not a technique I developed.

It's a technique that's actually been known

about for several centuries.

And we now know the underlying mechanism.

So today's discussion will give to you

many tools that you can apply.

All of these tools are, of course, behavioral tools.

They're completely zero cost.

And in telling you how those tools work,

you'll learn a lot about how the breathing, a.k.a.

the respiratory, system, works and how it interfaces

with the other organs and tissues of the body,

in particular the brain.

In fact, one of the most important things

to understand about breathing right here at the outset

is that breathing is unique among brain and bodily

functions in that it lies at the interface between our conscious

and our subconscious behavior.

And it represents a bridge literally

in the brain between the conscious and the subconscious.

What do I mean by that?

Well, breathing does not require that we pay attention

to our breathing or that we are even

aware that we are breathing.

It will just carry on in the background either normally

or abnormally, and I'll teach you

what normal and abnormal breathing is in a little bit.

However, breathing is unique among brain and bodily

functions in that at any moment, we can consciously

take control of how we breathe.

This is an absolutely spectacular and highly unusual

feature of brain function.

For instance, your digestion is carrying on

in the background right now whether or not

you've had food recently or not.

But you can't simply control your digestion

by thinking about it in a particular way.

In fact, most people can't even control their thinking

by trying to control their thinking.

That actually takes some practice.

It can be done-- a topic for a future episode.

However, breathing is unique.

Breathing will carry on involuntarily, subconsciously

in the background, as I said before.

But if, at any moment, you want to hold your breath or inhale

more deeply or vigorously or exhale longer than you inhale,

you can do that.

Very few, if any, other neural circuits in your brain and body

allow that level of control.

And it turns out that level of control is not an accident.

It has been hypothesized that by controlling breathing,

the brain is actually attempting to control

its own state of mind.

Now, the way this was originally stated in a scientific research

paper was a little bit different.

It was a little bit physiological.

The statement was, "The brain, by regulating breathing,

controls its own excitability."

Excitability in the context of neurobiology

is how able the brain is to take in new information or not,

how able the brain is or not to turn itself off to go to sleep

and to regulate its own levels of anxiety, focus, et cetera.

If that seems a little bit abstract,

I'll make it simple for you.

By changing your pattern of breathing,

you can very quickly change what your brain is capable of doing.

In fact, a little bit later, I'll

tell you that while you inhale, you

are far better at learning and remembering information

than during an exhale.

And it is a very significant difference.

Does that mean you should only inhale and not exhale?

No, of course not.

I'll teach you how to breathe for the sake of learning

and memory as well as for physical performance

and a number of other things.

So hopefully I've been able to highlight for you

the importance of breathing not just for life,

because, yes, breathing is essential for life,

but that the subtleties of how we breathe,

the duration and intensity of our inhales

and our exhales, how long we hold our breath between inhales

and exhales, very critically defines our state of mind

and our state of body, what we are able to do

and what we are not able to do.

And the great news is we can control our breathing

and, in doing so, control our mental health, physical

health, and performance.

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 breathing.

And, of course, we breathe in order

to bring oxygen into the body.

But we also breathe to remove certain things from our body,

in particular carbon dioxide.

So the main players in today's discussion

are going to be oxygen and carbon dioxide.

Now, a common misconception is that oxygen is good

and carbon dioxide is bad.

That's simply not the case.

Let's just take a step back from that statement,

and let's think about this.

When we breathe in, we are largely

breathing in air in order to bring oxygen into our body.

And we can just stop right there and say,

why do we breathe at all?

Why can't we just get oxygen from the world around us?

Well, it's because oxygen can't diffuse through our skin

into the deeper cells of our body.

Other single cell and very simple organisms

can actually bring oxygen into their system

without the need to breathe.

But we have to breathe in order to bring oxygen

to the cells that reside deep in our body.

In particular, our brain cells, which

are the most metabolically active cells in our body,

require a lot of oxygen. And those brain cells

are sitting, of course, in the brain, which

is encased in the cranial vault, the skull.

And so oxygen can't simply pass to those cells.

So we need to have a system that will deliver oxygen

to those cells.

We also need a system, which turns out

to be the breathing or respiratory system, that

can offload or remove the gas that we call carbon

dioxide, not because carbon dioxide is bad

but because too much of it in our system is not good.

In fact, much of today's discussion

will also center around the common misconception

that carbon dioxide is something that we want to get rid of.

You don't want to get rid of too much carbon dioxide or else

you can't actually get oxygen to the cells and tissues

of your body in an efficient way.

So you need oxygen and you need carbon dioxide in your body.

You also need to be able to offload or remove

carbon dioxide and bring in oxygen in the correct ratios

so that you can perform the kind of mental functions

and physical functions that you want to.

So if we just dial out even further,

we say, what are the key components of breathing?

What are the elements within the body that

allow us to bring oxygen to the tissues and cells

as is required and remove carbon dioxide from the body

as is required and yet keep enough carbon dioxide around

in order to allow oxygen to do its thing?

Well, that breathing or respiratory apparatus

has two major components, and I'm

going to just briefly describe those.

And as I do this, I really want to highlight the fact

that any time you're thinking about biology and physiology

in particular, whether or not it's about the brain

or the liver or the gut microbiome,

it's useful to categorize things either as mechanical mechanisms

or chemical mechanisms.

What do I mean by that?

Well, let's just take the analogy of hunger.

There are mechanical mechanisms that

tell us when we should eat.

For instance, you have neurons, nerve cells in your gut

that signal how stretched or nonstretched

the walls of your stomach are, how full

or how empty your gut is, and send that information

to the brain to make you feel to some extent hungry or not

hungry.

In general, when our stomach is very full

and especially if it's very distended, even with liquid,

it suppresses our hunger.

Whereas when our stomach is devoid of that mechanical

pressure, especially for a number of hours,

it tends to trigger hunger by signaling

via neurons to the brain.

In addition, there are chemical signals that go from the gut

to the brain.

For instance, we have neurons in our gut

that can detect the presence of amino acids

from proteins that we eat, fatty acids from the foods

that we eat, the lipids, and sugars, different forms

of carbohydrate.

The neurons in our gut are paying attention to

or respond to how much amino acid, fatty acid,

and carbohydrate is in our gut and sends signals

to the brain to either stimulate or suppress hunger.

So those are chemical signals that

are being passed from gut to brain,

and they work in parallel with the mechanical signals.

And this idea of "in parallel with,"

again, is a very common theme in biology,

especially neuroscience.

The term parallel pathways refers to the fact

that any time there's a critical bodily function,

it's very unlikely that just one type of information,

like just mechanical information,

is going to be used. / Almost always,

it's going to be mechanical and chemical information.

I could pick a number of other examples.

For instance, if you want to avoid

damaging your skin or other tissues of your body, which

is essential to life, well, then you have mechanical information

about, for instance, whether or not something

is pinching or ready to pierce your skin.

That's mechanical information.

It's sent via specific neurons up to the brain

to signal a retraction reflex if you

move your limb away from wherever that intense pressure

is coming.

You also have chemical sensing in your skin,

the presence of things that elicit a burn

or that elicit itch or that elicit extreme cold.

All of that chemical information is

being signaled up to the brain as well in parallel.

So parallel pathways is a common theme.

So when we're thinking about the respiration, a.k.a.

the breathing, system, we also need

to look at the mechanical system.

What are the different components

of the nose, the mouth, the lungs, et cetera, that

allow oxygen to be brought in and carbon

dioxide to be removed from the body but not too much carbon

dioxide removed to allow breathing

to work as efficiently and as optimally as possible?

And then we also need to look at the chemical systems

of the lungs, the bloodstream, and how different cells use

oxygen and carbon dioxide in order

to understand that as well.

If you can understand the mechanical and chemical aspects

of breathing, even just at a top contour,

well, then the various tools that I

discuss during today's episode, such as the ability

to calm yourself down most quickly by doing what's

called a physiological sigh--

I'll go into this in more detail in a little bit,

but this is two very deep inhales through the nose.

So the first one is a long inhale [INHALES DEEPLY],,

and then the second one after that is [INHALES SHARPLY]

a quick, sharp inhale to maximally inflate your lungs,

followed by a full exhale through the mouth to lungs

completely empty.

So it's big inhale through the nose,

then short inhale through the nose

immediately after that in order to maximally inflate the lungs,

and then a long exhale through the mouth

until your lungs are empty.

You will understand why that particular pattern of breathing

and not simply one inhale or not simply

an inhale through the nose and an exhale through the nose

as well is optimal for reducing your stress quickly.

That double inhale through the nose followed by a long exhale

through the mouth works to reduce your levels of stress

and lower your levels of so-called autonomic arousal

very fast in real time.

And it works better than any other known approach.

It's not a hack.

This is actually something that your body has

specific neural circuits to do, and it actually

performs during sleep on a regular basis and even

throughout the day, and that you can perform voluntarily.

And it works so well to reduce stress

very quickly not because it brings

in the maximum amount of oxygen and removes

the maximum amount of carbon dioxide but,

rather, because it optimally balances oxygen and carbon

dioxide.

If you understand the mechanical and chemical aspects

of breathing, then you will understand exactly why

that particular pattern of breathing,

the so-called physiological sigh,

is the most efficient way to rapidly reduce

stress in real time.

If you can understand the mechanical and chemical aspects

of breathing, you will also understand why

most people are overbreathing.

That is, they're breathing too often, even if they're

breathing in a shallow manner.

They're breathing too often.

And they are blowing off or removing too much carbon

dioxide.

And if you understand that carbon dioxide is

critical for the way that oxygen is delivered

from the bloodstream to the tissues of the body,

including the brain, well, then it

will make very good sense as to why

people who are breathing too much

don't actually experience all the effects of elevated oxygen,

but, rather, they're putting their body into what's

called a hypoxic state.

They're not getting enough oxygen

to the tissues of their body, in particular their brain.

And this is true not just for people who are obese

or who suffer from sleep apnea, although that's certainly

the case, but for people that have, believe it or not,

certain personality types.

We'll talk about breathing and personality type

and actually how breathing has been

shown to alter personality.

That's right.

Breathing can alter personality in positive ways that

allow anyone to show up to the various social and nonsocial

endeavors of their life with more calm, more focus,

alertness, and improve their overall health.

OK, so let's talk about the mechanical components

of breathing.

It's really quite simple.

You've got your nose, obviously, and you've got your mouth.

And a little bit later, we'll talk

about the incredible advantages of being a nasal breather

most of the time but also the incredible advantages

of using your mouth to breathe both for inhales and exhales

during particular types of endeavors.

And we'll get back to that a little later.

But for the meantime, the only two ways

to bring air into your system are through your nose

and through your mouth.

We also have the larynx, which is a rigid tissue or pipe that

brings the air from the nose and mouth down to the lungs.

Now, that word rigid is really important here

because what we will soon learn is that your lungs basically

act like a pump.

You sort of know this already.

But these are two big bags basically

that can fill with air or that can squeeze air out.

Now, what most people don't realize

is that the lungs are not just too big bags of air.

Your lungs are actually too big bags of air that inside of them

have hundreds of millions of little sacs

that are called the alveoli of the lungs.

And by having those hundreds of millions of little sacs,

you increase the surface area of the lungs.

And by increasing the surface area,

you allow more oxygen to pass from the air in your lungs

into the bloodstream than if you didn't have those sacs.

And you allow more carbon dioxide

to move from the bloodstream into those sacs of the lungs,

and then when you exhale, the carbon dioxide can be removed.

So those little sacs we call alveoli of the lungs

are an important part of the mechanical aspect

of breathing we'll get to a little bit later.

So at a first pass, the mechanical aspects of breathing

are really straightforward.

You can breathe through your nose.

You can through your mouth.

It goes down through the larynx.

I told you the larynx is a rigid pipe.

The lungs are not rigid.

They can expand and they can contract

like a pump to bring in air or to expel air.

Keep in mind that the lungs do not

have any muscles themselves.

So we need muscles that can either squeeze the lungs

or that will allow the lungs to expand.

And there are two general groups of muscles that do that,

and they are the diaphragm and the so-called intercostal

muscles.

The diaphragm is a thin muscle that sits below the lungs

and above the liver.

And when we inhale, provided that we

are using what's called diaphragmatic breathing, that

diaphragm contracts.

And when it contracts, it moves down,

which allows more space for the lungs to inflate with air.

Now, the intercostal muscles are the muscles between our ribs.

A number of people probably don't realize this.

But your ribs, of course, are bone,

but in between those bones, you have muscles.

And the intercostal muscles, when you inhale,

contract, and that allows your rib cage to move up

and to expand a bit.

And I think, again, people probably

don't realize that your ribs are not fixed in place.

They can actually get further and closer apart

from one another.

So when you inhale, your rib cage actually moves up.

Sometimes the shoulders will move up as well.

And that's because those intercostal muscles

are contracting.

Now, muscles can't move on their own.

They are controlled by nerves.

So we've got the nose, the mouth, the larynx,

and the lungs.

The lungs have all those little alveoli in them.

And as I told you, we've got the diaphragm

as a muscle to move the lungs, and we

have the intercostal muscles to move the ribs, which

can allow the lungs to expand.

Again, we're just on the mechanical components

of breathing.

But because muscles can't move themselves,

you should be asking, what moves the muscles?

And it's really nerves that control muscles.

So whether or not you're contracting your biceps

or you're walking and you're contracting your quadriceps

and your hamstrings and your calf muscles,

it's neurons, nerve cells that control that.

There's a specialized nerve called the phrenic nerve,

P-H-R-E-N-I-C, phrenic nerve, that comes out of the neck.

And when I say it comes out of the neck, what I mean

is that there are little neurons that reside in the brainstem,

in the back of your brain, and they send little wires

that we call axons down and out of the neck.

They go close to the heart and a little bit behind it.

And they go down, and they form synapses.

That is, they form connections with the diaphragm.

And when those neurons release neurotransmitters, which

are little chemicals, the diaphragm contracts,

and it moves down.

So we say that the phrenic nerve is a motor nerve.

It's designed to move muscle.

However, the phrenic nerve, like a few other nerves in the body,

is interesting in that it has not just motor nerves in there,

neurons that control the contraction of muscles.

It also can sense things, has sensory neurons.

So it also sends connections down to the diaphragm

and actually down deep into the diaphragm

and close to the liver.

And note that I said liver twice now already,

and we're going to get back to this later

when we talk about physical movement

and cramps of the body.

Those sensory neurons dive deep into the diaphragm.

And then they go back up to the brain,

and they allow you to sense where the diaphragm is.

So they're giving information about where

the diaphragm is in your body.

Now, most of the time, you're not paying attention to this.

But right now, you can actually try this.

And I would encourage you to do this.

Diaphragmatic breathing is, in many ways,

the ideal way to breathe and that it's the most efficient

way to breathe.

We'll talk about what we mean exactly when we

say breathing efficiency later.

But the diaphragm is designed to allow

the lungs to expand or to contract the lungs,

to bring air into the body or to remove

carbon dioxide from the body.

And if you want to know whether or not

you're using diaphragmatic breathing, it's very simple.

If you inhale-- probably best to do this through the nose,

but you could do it through the mouth.

If you inhale and your belly moves outward on the inhale,

well, then that phrenic nerve is controlling your diaphragm

properly.

And then when you exhale, your belly

should go in just a little bit.

That's diaphragmatic breathing.

Now, diaphragmatic breathing is talked

about in the context of yoga.

It's often talked about as a way to calm down and so on.

But diaphragmatic breathing is just one mode

by which your brain and the phrenic nerve

can control muscle, the diaphragm,

to control the mechanical aspects of the lungs

to bring in air and expel air.

As I mentioned before, you also have

these muscles between your ribs or the intercostal muscles.

And there's a separate set of nerves

that allow those muscles to contract and for your rib cage

to expand in order to create more room for your lungs

to get larger and fill with air or for your rib cage

to contract a bit when those muscles relax in order

to expel air.

I'd like to go on record by saying

that there is no rule that diaphragmatic breathing is

better than breathing where your rib cage moves.

This is a common misconception.

People say, oh, if your shoulders are going up and down

and your rib cage is moving while you're breathing,

well, then you're not breathing right.

And if your belly goes out and the rest of your body

is still while you breathe, well, then you're

breathing correctly.

I know of zero--

in fact, zero minus one data to support that statement.

You have multiple parallel mechanisms

to control the mechanics of your lungs and for breathing.

And when you're exerting yourself very hard,

you tend to use both the intercostal muscles

and your rib cage moving as well as your diaphragm in order

to bring in a lot of oxygen and to offload

a lot of carbon dioxide.

And when you're calmer, frankly, you

could use diaphragmatic breathing

or you could use rib cage type breathing in order

to bring enough oxygen into your system.

There's no real data showing that diaphragmatic breathing is

somehow better or worse.

However, being able to mechanically control those

independently or to combine them and use them together

is of tremendous power toward regulating

your mental and physical states.

And we'll talk about how to do that a little bit later.

For right now, please understand that you

have these different mechanical components that

allow you to bring oxygen into your system and to expel air

and to thereby offload carbon dioxide from your system.

Again, we haven't talked about the gas exchange of carbon

dioxide and oxygen and how that's

happening in the bloodstream.

We'll talk about that next.

But the basic mechanical components are pretty simple.

Once again, just to review, it's nose, mouth, larynx, lungs,

alveoli within the lungs, and then those two muscles,

the diaphragm and the intercostal muscles

of the ribs.

And one thing I failed to mention

is why it's so important that that larynx be rigid, that it's

a tube that is very rigid.

And the reason for that is that unlike the lungs, which

you want to act as sort of a bellow pump

where you can deflate it and inflate it in order to move air

in and out, the larynx needs to be rigid

so that it doesn't collapse while you're bringing air

in and out.

You can imagine that if it was a very flimsy tube or the walls

of the larynx were very flimsy and thin,

well, then you can imagine breathing in very vigorously,

and it would shut like a tube that

suddenly flattens on itself, which would not be good.

So the fact that the larynx is rigid

is actually a very crucial part of this whole system.

The other important aspect of this system

as it relates to the mechanics of breathing

is the fact that your nose and your mouth

have different resistances to air.

You can probably notice this right now

if you were to, for instance, breathe

in through your mouth [INHALES] and only

through your mouth versus breathing

through your nose [SNIFFS].

Some of you perhaps have a harder time breathing in

through your nose.

By the way, it's perfectly normal

that one or the other nostril would

be harder to breathe through or easier to breathe through

and that switches across the day.

It has to do with the flow of mucus and cerebrospinal

fluid and intracranial pressure.

Totally normal.

Many people out there think they have

a deviated septum who don't actually

have a deviated septum.

A little bit later, we'll talk about how

to repair a deviated septum without surgery because that

actually is possible in many, not all, cases

and is immensely beneficial to do.

But what we know is that breathing in through the nose

is a little bit harder, and it's supposed

to be a little bit harder.

However, because it's a little bit harder because there's

more resistance, as we say, you are actually

able to draw more force into these mechanical aspects

of the breathing apparatus and actually

bring more air into your lungs.

You can try this right now.

Try breathing in through your mouth to maximally inflate

your lungs and try and do it through mostly diaphragmatic

breathing, just for sake of example.

In other words, try and breathe in through your mouth.

And as you do that, have your belly expand and maximally

inflate your lungs.

I'll do it right now with you so that we can do it together

and I can prove to everyone that I'm just as

deficient in this as you are.

[INHALES]

OK, so I can inflate my stomach doing that.

But now try doing it with your nose,

and please do exhale before you try doing it with your nose.

With your nose, you're going to feel more resistance,

but you'll notice that you can inflate it quite a bit further.

[SNIFFS] And you'll feel your entire cavity, your belly

and maybe even in your lower back, fill with some pressure.

So the increased resistance actually

allows you to draw more air into the system.

This turns out to be very important.

And it also wipes away a common misconception,

which is if you're somebody who has challenges breathing in

through your nose, that somehow you should avoid breathing in

through your nose, actually, quite the opposite is true.

And we can go a step further and say

that if you have challenges breathing in through your nose,

chances are that's because the increased

resistance of breathing in through your nose,

provided it's not completely occluded,

is going to allow you to bring more oxygen into your system.

This will turn out to be useful later when

we explore different techniques, for instance,

not just to calm down quickly but to elevate

your energy quickly, to remove a cramp during exercise,

and a number of other things that breathing

can be used for that can be immensely

useful for mental and physical challenges.

I'd like to take a quick break and acknowledge

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So now let's talk about the chemical aspects of breathing.

And the two major players in this discussion

are oxygen, which all the cells and tissues of your body need,

and carbon dioxide, which all the cells

and tissues of your body need.

In fact, carbon dioxide plays critical roles

in delivering oxygen to your cells.

And without carbon dioxide, you're

not going to get enough oxygen to the cells

and tissues of your body.

That said, if carbon dioxide levels are too high,

that is very problematic.

In fact, one of the ways that one can reliably induce panic

in anybody is to have them breathe

air that contains too much carbon dioxide,

so much so that for people that lack

a so-called amygdala-- many of you

have probably heard of the amygdala.

This is a brain area that's associated with fear and threat

detection.

Even in people who completely lack amygdalas

on both sides of the brain because they were removed

because they had epileptic seizures there

and, therefore, those people are completely unafraid of things

that they ought to be afraid of like heights,

poisonous snakes, any number of different things

dangerous to humans, well, if those people

breathe an excess amount of carbon dioxide,

they immediately have a panic attack.

What that tells us is that, again, there

are parallel mechanisms, there's redundancy in the system

to protect ourselves from having too much carbon

dioxide in our system.

So we need enough carbon dioxide and enough oxygen in our system

but not too much.

The way that's accomplished is, of course, we breathe in air.

Our lungs inflate.

And if you recall those little alveoli of the lungs,

those little sacs, oxygen can actually move from the air

into those little sacs and then from those little sacs

into the vasculature-- the vasculature are

the capillaries, the veins, and the arteries of the body--

because the walls of those little alveoli

are exceedingly thin, and they have tons of little capillaries

that go into them and are all around them.

So this is amazing, right?

There's oxygen literally passing from inside

of these little sacs in our lungs

because we inhaled the oxygen from the air

into the bloodstream, and then that oxygen

gets bound up by proteins in the blood,

in particular hemoglobin.

And hemoglobin then delivers oxygen

to the various cells and tissues of the body.

However, oxygen can't just hop on hemoglobin and cruise

along with hemoglobin until it gets to, say, your brain

and then hop off.

It doesn't work that way.

You require carbon dioxide in order

to liberate oxygen from hemoglobin.

Carbon dioxide has this incredible property

of actually being able to change the shape of hemoglobin.

Hemoglobin is shaped as a sort of a cage around oxygen

molecules.

And when it's in that cage shape,

the oxygen can't be liberated.

So you've got oxygen and hemoglobin bound to one another

moving through your bloodstream.

But if a tissue needs oxygen, there

needs to be carbon dioxide present to open up that cage.

And that's what carbon dioxide does.

It allows that cage to change shape,

and then the oxygen can be liberated

and then can be delivered to the tissues,

whether or not that's brain tissue or muscle tissue,

so on and so forth.

And so those are the major chemical components

of breathing.

There are a few other aspects related

to the chemical components of breathing,

such as the fact that carbon dioxide is strongly related

to how acidic or how basic your body is in general.

So for instance, if carbon dioxide levels go way down,

your blood pH goes way up.

That is, you become more alkaline.

Now, for many people, the word pH and the whole concept of pH

immediately starts to evoke anxiety in and of itself.

pH is actually very simple.

You want the body basically to be at a pH of about 7.4.

There are some regions of your body,

in particular along the gut, for which that number is

importantly different in order for digestion to work properly.

You've all heard of the gut microbiome, the little microbes

that, provided you have enough of them

and they're diverse enough, allow your brain and body

to function optimally at the level of immune system, hormone

system, brain, et cetera.

Well, in the gut, you want the pH sometimes

be slightly more acidic.

Because when it's more acidic, the little microbiota

flourish far more than if it were more basic.

But basically, you want the rest of the body

to be at about pH 7.4.

If carbon dioxide levels go to low, the pH increases in a way

that you might say, oh, well, that's bad,

but that actually allows more oxygen

to be available to the tissues of your body, at least

temporarily.

We'll talk about this a bit more later.

If I'm losing any of you, just hang in there

because we're almost done with this whole business

of the mechanics and the chemistry of breathing,

and then we can get into the tools and revisit some of this

later to clean up any misunderstandings that

may have arisen.

But as we're talking about carbon dioxide over and over

again and how key it is to have carbon dioxide and the problems

with it going too high to low, you

should probably be asking yourself, what actually makes

carbon dioxide go too low?

We know that we breathe in oxygen,

and then it can pass from the lungs and the alveoli

into the bloodstream and that we need carbon dioxide to liberate

oxygen from the hemoglobin into the cells

and tissues of the body.

And we know that when we exhale--

well, actually, I haven't told you this yet.

But you should know that when you exhale,

carbon dioxide is actually taken from the bloodstream

back into the alveoli of the lungs.

And then when you exhale, it's expelled through your mouth

or through your nose out into the world.

So the way I just described all that-- inhale, bring in oxygen,

exhale, expel carbon dioxide--

pretty straightforward, right?

Indeed, it is.

And it also tells you that were you

to exhale a lot more or a lot more vigorously,

you would expel more carbon dioxide.

And in fact, that's exactly the way it works.

When you hyperventilate, of course, you

are inhaling more than usual, but you are also

exhaling more than usual.

So you're, of course, bringing in more air and oxygen

to your body.

But you're also removing more carbon dioxide from your body

than normal.

Carbon dioxide, because of the ways that it regulates brain

state-- in fact, the way in which it regulates

the excitability, literally the ability of your neurons

to engage electrically or not--

it can create states of panic and anxiety, which

is why when you hyperventilate, you

feel an increase in anxiety, or when

you feel an increase in anxiety, you hyperventilate.

It's a reciprocal relationship.

In fact, I don't want anyone who has anxiety

or who has panic attacks to try this now.

But for most people, it's probably safe

as long as you're not driving or doing something mechanical

or operating machinery, that is.

Probably safe to do 25 or 30 deep inhales and exhales.

And you'll notice that by about breath 10,

you'll start to feel tingly, and you'll probably

feel a little bit more alert.

And, again, if you have anxiety or panic attack tendencies,

please don't do this.

But you will feel an increase in so-called autonomic arousal,

an increase in the activity of your overall sympathetic

nervous system, which has nothing to do with sympathy,

has everything to do with alertness.

You'll actually deploy adrenaline from your adrenals.

So I'll just do this now.

You can try this now, again, provided you're in a safe place

and you don't have anxiety or panic attack tendencies.

You would just breathe in through your nose

and out through your mouth.

Remember, we're breathing in more and more vigorously,

and we're exhaling more and more vigorously than we normally

would.

It goes something like this.

[INHALING, EXHALING]

Now, by breath 8 or 9 or 10, you'll

notice that your body starts to heat up.

That's due to a couple of things,

mainly the release of adrenaline from your adrenals.

I'm already feeling a little bit lightheaded.

The lightheadedness is actually because your vasculature,

the capillaries and veins and, to some extent,

even the arteries of your body and particularly in your brain,

are actually starting to constrict.

So you're cutting off blood flow to the brain.

Why?

Well, because carbon dioxide actually is a vasodilator.

Normally, it exists in your body to keep capillaries, veins,

and arteries dilated to allow blood to pass through them.

When you hyperventilate, sure, you're

bringing in a lot of oxygen, which

you think would make you more alert, and, indeed, it does.

But you are also expelling a lot more carbon dioxide

than you normally would.

And that's causing some vasoconstriction,

and you're going to start feeling

tingly in the periphery, in your fingers and toes

perhaps or your legs.

You will also notice that you're feeling more alert in the brain

but that you might start to feel a bit of anxiety.

So hyperventilation, yes, brings in more oxygen,

also removes more carbon dioxide.

The removal of excess carbon dioxide

puts you into a state that's called hypocapnic, hypoxia.

Hypoxia is reduced levels of oxygen relative to normal.

Hypocapnia is reduced levels of carbon dioxide

relative to normal.

And it is those reduced levels of carbon dioxide

that are largely responsible for that elevation

in energy and at the same time a feeling of a bit of anxiety,

the construction of the microvasculature

in the brain and body, and therefore

the feelings of being kind of tingly

and having kind of an urgency to move.

OK, so by now, it should be clear

that we need both oxygen and carbon dioxide.

And across the course of this episode,

I will explain how to adjust those ratios of oxygen

to carbon dioxide depending on what your immediate needs are

and what you plan to do next, whether or not

that's sleep or exercise or mental work, et cetera.

Before going any further, however, there

is something I want to touch on.

Because even though not everyone will experience this,

I think enough people experience it

that it is of interest, and now's

the right time to touch into what happens when you go up

to a very high altitude, meaning why it's hard to breathe when

you get up to high altitudes.

So if you're close to sea level, you

are getting out of the optimal balance of oxygen

in the air you breathe.

As you ascend in altitude-- so let's

say you go to 6,000 feet or 10,000

or maybe even 11,000 feet above sea level.

Or maybe you're one of those rare individuals that

climbs Denali, or you climb Mount Everest,

and you get up there, and you notice that most people are

going to wear an oxygen mask.

Why is it that you need an oxygen mask at those very high

altitudes or when people do these very high altitude

skydives that they need oxygen way up high?

Well, a lot of people will say, oh, there's not much oxygen

up there.

The air is thinner.

OK, well, perhaps a better way to think about it

is that, remember when we were talking

about the mechanical aspects of breathing and the fact

that the lungs don't really move themselves,

that they have the muscles, the diaphragm

and the intercostal muscles to move them?

Well, a lot of the reason why your lungs can fill so readily

with air is that when you don't have much air in your lungs,

there's very low air pressure in your lungs relative to outside

you.

So what we mean then is if you were

to open up your mouth [INHALES] or your nose

and breathe in, that is, breathe in through your nose

or mouth, what's going to happen is

air is going to move from high pressure to low pressure.

So it's very easy to fill your lungs.

Even though you need those muscles

to move the various things around that

allow your lungs to fill, the air

is going to go from high pressure to low pressure.

So [INHALES] for those of you listening,

I just took a big inhale through my nose.

And then when you exhale, you're basically taking the lungs

from a state in which the pressure is

really high in the lungs, high pressure,

like a balloon that's full--

and the pressure in your lungs when your lungs are full

is higher than the air outside.

So it's pretty easy [EXHALES] to expel that air

through the nose or mouth.

When you're at high altitudes, the air pressure is lower.

And so what happens is when the air pressure is lower

outside your body and your lungs are not full of air,

you don't have that really steep gradient

of high pressure outside the body

to low pressure inside your lungs.

And so you actually have to put a lot more effort

into breathing air into your lungs.

You have to really exert a lot of force.

You have to get the diaphragm, those intercostal muscles

working really hard.

You might even find that your shoulders are lifting

with each breath [INHALES] because you really

have to generate a lot of force to get enough air

and oxygen into your lungs.

Now, an important principle to understand

is that in humans, and in some other species,

but really what we're talking about now

is humans, when you inhale, that's an active process.

You really need to use those muscles

of the intercostals and the diaphragm

in order to inflate the lungs.

But the whole process is made easier

when air pressure outside your body

is higher than it is in your lungs

because then they're going to fill up really readily.

Exhaling, at least for humans, is a passive thing.

You just have to relax the diaphragm

and relax the intercostals and let the rib cage kind of fall

back to its original position.

So inhaling is active, and exhaling is passive.

And so what happens is if you're at a high altitude

and the air pressure is very low,

then you have to put a lot of energy

into breathing air into your lungs

to get an equivalent amount of oxygen into your lungs

and then into the bloodstream.

So that's why when you arrive at a high altitude location,

for the first few days, you're going to feel lightheaded

maybe a headache.

You're also going to have more buildup of carbon

dioxide in your system.

And so the whole balance of oxygen and carbon dioxide

is going to be disrupted.

I mention all that because, yes, indeed, there

are some changes in the atmospheric gases

at high altitudes, and that can impact

how much oxygen you can bring into your system,

into your tissues.

But I've heard many explanations of why it's hard to breathe

or why you feel lousy at altitude.

Well, you just discovered one reason,

which is that you don't have that steep high pressure

to low pressure gradient from the outside of the body

into the inside of the body.

The converse is also true.

If you've been at altitude for a few days

and you've had the opportunity to adjust-- a lot of athletes,

for instance, will go train at altitude.

It's hard for them in the first days or weeks,

and then they get really good at training at altitude.

There are a number of different adaptations

that occur in terms of the amount of oxygen

that can be carried in the blood by hemoglobin

and the interactions between carbon dioxide and hemoglobin

and oxygen that allow more oxygen

to be delivered to the tissues, such that, at altitude,

you can function just normally.

But if you then move very quickly from altitude-- say,

you've been training at 8,000 feet or 10,000 feet.

You've been hiking up at that high level, and you've adapted,

and you come down to sea level.

Well, for about two to five days,

you're going to feel like an absolute beast.

You're going to be able to essentially deliver

far more oxygen to your muscles per breath.

In part, that is because of the way

that the hemoglobin and the oxygen that it's carrying

has been altered when you were at high altitude.

But it's also because when you were at that high altitude,

those intercostal muscles and those diaphragms

got trained up quite a bit and allowed you to generate more

air volume for every breath.

In other words, those muscles got stronger,

and you got more efficient at driving the phrenic nerve

consciously to [INHALES] really breathe in a lot of oxygen

so you don't feel lightheaded, headache, et cetera.

OK, so that's a little bit of an aside.

But it's an important aside, I believe, because, A,

it answers a question a lot of people ask

and they a lot of people wonder about and, B,

because it incorporates both the mechanical aspects of breathing

and the chemical aspects of breathing.

I realize it's a little bit of a unusual circumstance.

But now if anyone asks you why it's

hard to breathe at altitude, you know

it has to do with this lack of a high pressure

to low pressure gradient across the body

and with the atmosphere outside you.

It's also an opportunity for me to say

that if you do find yourself at altitude

and you have a headache or you're feeling like you just

can't catch your breath, spending some time really

consciously trying to draw in larger breaths of air,

as much as that might seem fatiguing

and you'll be short of breath, it will allow

you to adapt more quickly.

And a little bit later in the episode,

we'll touch on a few methods, including

deliberate hyperventilation combined with some breath

holds, that can allow you to deliver more

oxygen to the cells immediately upon arriving

at altitude so you don't get quite

as much headache, disorientation, and so on.

So leaving breathing at altitude aside let's

all come back down to the same conceptual level.

We can ask ourselves, for instance,

what is healthy breathing, and what is unhealthy breathing?

And the first place we want to tackle this

is within the context of sleep.

So when we go to sleep at night, we continue to breathe.

That's no surprise.

If we didn't, we would die during sleep.

However, there is a large fraction

of the population that underbreathes during sleep.

They're not taking deep enough or frequent enough breaths.

And therefore, they are experiencing

what's called sleep apnea.

They are becoming hypoxic, hypo-oxic.

There's less oxygen being brought into their system

than is necessary.

People that are carrying excess weight,

either fat weight or muscle weight or both,

are more prone to nighttime sleep apnea.

However, there are a lot of people

who are not overweight who also experience sleep apnea.

How do you know if you're experiencing sleep apnea?

Well, first of all, excessive daytime sleepiness

and excessive daytime anxiety combined

with daytime sleepiness is one sign

that you might be suffering from sleep apnea.

The other thing is if you happen to snore,

it's very likely that you are experiencing sleep apnea.

And I should mention that sleep apnea is a very serious health

concern.

It greatly increases the probability

of a cardiovascular event, heart attack, stroke.

It is a precursor or sometimes the direct cause

of sexual dysfunction in males and females.

Cognitive dysfunction during the daytime.

It can exacerbate the effects of dementia,

whether or not it's age-related dementia of the normal sort

or Alzheimer's type dementia, which

is an acceleration of age-related cognitive decline.

If you're somebody who has had a traumatic brain

injury, if you're experiencing a lot of stress,

sleep apnea is going to greatly disrupt

the amount of oxygen brought in to your brain and body

during sleep and is going to lead

to a number of nighttime and daytime issues.

So it's something that really needs to be addressed.

And we'll get into this a bit more later.

But since I raised it as a problem,

I do want to raise the solution.

One of the major treatments for sleep apnea

is that people will get a CPAP device, which

is this face mask and a machine that they'll sleep with.

And while those can be very effective,

not everyone needs a CPAP.

One of the more common methods nowadays

that's being used to treat sleep apnea,

which is purely behavioral, an intervention,

and is essentially zero cost, is that people

are starting to shift deliberately

to nasal breathing during sleep because

of the additional resistance of nasal breathing

and because of the fact that there's

far less tendency if any, excuse me, to snore

when nasal breathing.

Taping the mouth shut using medical tape prior to sleep--

excuse me.

Putting medical tape on the mouth prior to going to sleep

and then sleeping all night with medical tape on the mouth

is one way that people can learn to nasal breathe during sleep

and can greatly offset a lot of sleep apnea, snoring,

and sleep-related issues.

A number of people don't want to or don't

feel safe putting medical tape on their mouth prior to sleep.

For some reason, they think they're going to suffocate.

But, of course, you would wake up

if you start to run out of air at any moment.

So that's not so much a concern.

But what they'll do is they will start

to use pure nasal breathing during any type of exercise

or even just for some period of time walking during the day

or while working.

And, again, later, we'll get into the enormous benefits

of shifting to pure nasal breathing when not exercising

hard, meaning at a rate that you could normally

hold a conversation-- although if you're pure nasal breathing,

you won't be holding that conversation--

or when simply doing work or any number of things

that are of low intensity.

You can train your system to become a better nasal breather

during the daytime through these deliberate

actions of taping the mouth shut or just being conscious

of keeping your mouth shut.

And that, in addition to having a number of positive health

and aesthetic effects during the daytime,

is known to also transfer to nighttime breathing patterns

and allow people to become nasal breathers as opposed

to mouth breathers during sleep and to snore less

and to have less sleep apnea.

Again, if you have severe sleep apnea,

you probably do need to check out a CPAP.

You should talk to your physician.

But for people who have minor sleep apnea or sleep

apnea that's starting to take hold,

these other methods of shifting to becoming a nasal breather

are going to be far more beneficial and far more cost

effective than going all the way to the CPAP, which, by the way,

doesn't really teach you how to breathe properly

as much as it does adjust the airflow going into your system.

That's an important point, that when you shift from mouth

to nasal breathing during sleep, you're

actually learning and training your system

to breathe properly.

And when I say learning and training

your system to breathe properly, what do I mean?

Let's put some scientific and mechanistic meat on that.

We already talked about the phrenic nerve, this nerve

that innervates the diaphragm and that allows for the lungs

to fill up because of the movement of the diaphragm.

What we didn't talk about, however,

were the brain centers that actually

control the phrenic nerve and control breathing.

Knowing about these two brain areas and what they do

is extremely important, not just for understanding the content

of this episode but for understanding all of the tools

that we'll discuss and, indeed, your general health as it

relates to respiration.

So there are basically two areas of the brain

that control breathing.

The first is called the pre-Botzinger complex.

You don't have to worry about the name so much.

Just know that it was named after a bottle of wine

and that it was discovered by the great Jack Feldman, who's

a professor of neuroscience at the University of California,

Los Angeles.

This is one of the most fundamental discoveries

in all of neuroscience in the last hundred years

or more because this brain area that Jack and his colleagues

discovered controls all aspects of breathing that are rhythmic,

that is, when inhales follow exhales

follow inhales follow exhales.

That's all controlled by a small set

of neurons in this brainstem area,

so around the region of the neck,

called the pre-Botzinger complex.

And we really owe a debt of gratitude

to Jack and his colleagues for discovering that area

because it's involved in everything from breathing when

we're asleep to breathing when we're not

thinking about our breathing.

It may have a role--

that is, when its function is disrupted,

it may cause things like sudden infant death syndrome.

Believe it or not, it can explain

in large part many of the deaths related to the opioid crisis

because exogenous opioids like fentanyl and other sorts

of drugs, which are opioids obviously,

bind to opioid receptors on that structure and shut it down.

Now, keep in mind these neurons are designed

to be incredibly robust and are designed to fire inhale,

exhale, inhale, exhale no matter if we're awake or aware,

unaware or asleep to keep us alive.

Exogenous opioids like fentanyl and drugs

that are similar to that can shut down that structure

because it's rich with these opioid receptors.

So it binds to that, and it shuts off

the pre-Botzinger complex, which is

the major cause of death of people

who die from opioid overdoses.

I think a lot of people don't realize that.

They think, oh, the opioids must shut off the brain

or shut down the heart.

No, it shuts down breathing.

So Jack's discovery no doubt will

lead to some important things as it relates to addiction,

and hopefully I think we frankly can expect that it's also

going to eventually lead to ways to prevent death in people

using opioids or other types of drugs,

maybe by blocking opioid receptors

in pre-Botzinger complex using things

like naltrexone, et cetera.

In any event, pre-Botzinger complex

is controlling inhale, exhale, inhale, exhale patterns

of breathing.

The other brain center controlling breathing, again,

through the phrenic nerve--

it all converges and goes out through the phrenic nerve

in these intercostal muscles--

is the so-called parafacial nucleus.

And the parafacial nucleus is involved in patterns

of breathing where there is not an inhale followed by exhale,

inhale followed by exhale-- that is, it's not rhythmic,

one than the other--

but, rather, where there is a doubling up of inhales

or a doubling up of exhales or a deliberate pause in breathing,

so inhale, pause, exhale, pause, inhale, pause, exhale, pause,

this sort of thing.

A little bit later, we'll talk about a pattern

of breathing called box breathing, which

has very specific and useful applications,

in particular for adjusting anxiety.

And in that case, it involves going from rhythmic breathing

of inhale, inhale, inhale, exhale, that is,

relying on the pre-Botzinger complex neurons,

to reliance on the parafacial nucleus neurons and box

breathing, just to give away what's probably

already obvious, as you inhale, hold, exhale, hold, and repeat.

And that pattern of breathing, even though it's

rhythmic in nature because inhales precede exhales precede

inhales and so on, there's a deliberate breath hold

inserted there.

So anytime we're taking conscious control

of our breathing, the parafacial nucleus is getting involved.

Now, you don't have to assume that the parafacial nucleus is

the only way in which we take conscious control

of our breathing.

We can also take control of the pre-Botzinger complex.

You can do that right now.

So for instance, you are breathing

in some specific pattern now that, unless you're

speaking or eating, no doubt is going to involve inhales

followed by exhales.

But you could, for instance, decide

that, yes, inhales are active and exhales are passive.

But now you're going to make the exhales active as well.

So rather than just inhale and then let your lungs deflate,

you could inhale [INHALES] and then force the air out.

[EXHALES] That's going to represent a conscious taking

over of control of the pre-Botzinger complex.

And so the reason I'm giving this mechanistic detail is, A,

it's super important if you want to understand all the tools

related to breathing.

B, it's actually a pretty simple system.

Even though the areas have fancy names

like pre-Botzinger or parafacial,

it's pretty straightforward.

You have one area that controls rhythmic breathing--

inhale follows exhales-- and the other area which gets involved

in breathing any time you start doubling up

on inhales or exhales.

In fact, the parafacial nucleus is the one

that you're relying on while you speak in order

to make sure that you still get enough oxygen.

It's also the one that you will use

if you incorporate the physiological sigh or box

breathing.

And, frankly, most of the time, you're

using both of these circuits or these brain systems,

parafacial and pre-Botzinger, in parallel.

Again, biology loves parallel systems,

especially for things that are so

critical that if we didn't do them, we would die,

like breathing.

And so it makes sense that we have two different brain

structures that control this.

So now you have an understanding of the mechanical control

of breathing, that is, the different parts

within the parts list that are involved in breathing,

everything from nose to mouth to alveoli, the lungs, et

cetera, and the muscles involved in moving the lungs.

You understand, I like to think, a bit about bringing oxygen

in and removing carbon dioxide but not so much carbon dioxide

that you can't actually use the oxygen that you have.

And you know about two brain centers,

one controlling rhythmic breathing and one that

controls nonrhythmic breathing.

I want to repeat something that I said a little bit earlier

as well, which is that breathing is incredible

because it represents the interface

between conscious and subconscious control

over your not just body, not just your lungs,

but that how you breathe influences your brain state.

So by using your brain consciously

to control your breathing, you are using your brain

to control your brain.

The best way I've ever heard this described

was from a beautiful, I should say now

classic paper in The Journal of Physiology, published

in 1988 from Balestrino and Somjen,

where the final line of their summary intro states,

"The brain, by regulating breathing,

controls its own excitability."

And just to remind those of you that

don't remember what excitability is,

excitability is the threshold at which a given neuron, nerve

cell can be active or not.

So when we breathe a certain way, the neurons of our brain

are more likely to get engaged.

They're more likely to be active.

And when we breathe in other ways,

our brain becomes harder to activate.

Its excitability is reduced.

Now, you might think excitability is a great thing.

You always want your brain to be excitable.

But that's actually not the case.

And, in fact, that very statement

that Balestrino and Somjen made led

to a number of other investigations

that were really important in defining

how if people overbreathe, that is,

if they hyperventilate, at rest, they expel, that is, they

exhale too much carbon dioxide, what

that classic paper by Balestrino and Somjen led to

was a number of different investigations

in humans looking at how different patterns of breathing

impact the overall state of the brain and the ability

of the brain to respond to certain what

are called sensory stimuli.

Keep in mind that your brain is always active.

The neurons are firing at low level, low level, low level.

But when you see something or hear something,

or you want to focus on something,

or you want to exercise or really listen to something

or learn, certain circuits in your brain

need to be more active than everything else.

That is, there needs to be really high what's

called signal to noise.

There's always a lot of noise and chatter in the background,

just like the chatter at a cocktail party

or at a stadium event.

In order to really pay attention, focus, learn,

all the incredible things that the brain can do,

you need that signal to get above the noise.

There's a beautiful paper that asks,

how does the pattern of breathing, in particular, how

does overbreathing, change the patterns of activity

in the brain?

This is a paper entitled "Effects

of Voluntary Hyperventilation on Cortical Sensory Responses."

And I will provide a link to the study in the show note

captions.

It's a somewhat complicated paper

if you look at all the detailed analyzes.

However, the takeaway from this paper is exquisitely simple

and I also believe incredibly important.

Basically, what it showed is that when

people hyperventilate, they expel, that is,

they exhale more carbon dioxide than they would normally.

So they become what's called hypocapnic, OK?

Carbon dioxide levels are low in the blood.

And over a short period of time, they

become low in the tissues of the body.

When that carbon dioxide level drops low,

you would say, OK, well, you're still

bringing in a lot of oxygen, because these people

are hyperventilating.

So they should feel really alert.

And, indeed, that's what happens.

The people feel very alert.

However, because they're not bringing

enough carbon dioxide in or, rather, the proper way

to say it would be because they're overbreathing,

exhaling too much, they are not retaining or keeping

in enough carbon dioxide.

Well, then that lack of carbon dioxide

means that the oxygen that they are breathing in

can't be liberated from the hemoglobin,

can't get to the brain.

And what they observe is about a 30% to 40%

reduction in the amount of oxygen that's

being delivered to the brain.

And the reduction in carbon dioxide

also prevents some of the normal patterns of vasodilation,

the dilating, the opening up of the capillaries,

so, again, less blood flow.

But most importantly, as it's shown in this paper,

the brain overall becomes hyperexcitable.

It's as if it's being starved of oxygen and blood flow.

And all the neurons in a very nonspecific way

start increasing their firing levels.

So the background activity is getting louder and louder.

It's like the rumble or the noise of a crowd at a stadium.

And as a consequence, the sensory input from a sound

or from a touch or from some other event in the world

doesn't get above the noise.

What this means is that when we hyperventilate,

because we aren't retaining enough carbon dioxide,

we are not getting enough oxygen to the tissues

that need oxygen. And as a consequence of that, the brain

becomes hyperexcitable.

We actually know that there's an increase in anxiety.

And we become less good, less efficient

at detecting things in our environment.

So we're not processing information as well at all.

The noise goes up, and the signal goes down.

Again, incredibly important set of findings.

I should also mention that hyperventilation

is one way that, in the laboratory anyway

or in neurosurgery units for some time,

physicians would evoke seizure in seizure-prone patients.

The reason that works is exactly the explanation

I just gave you.

Seizure is a excitability of the brain, not enough

inhibition or suppression of the overall circuitry.

So you get these waves or these storms of electrical activity.

Low levels of carbon dioxide in the brain because

of low levels of carbon dioxide in the blood

are one of the major triggers for seizures.

Now, I realize that most people listening to this

are not epileptic.

But nonetheless, this brings us all back

to this question of what is normal healthy breathing.

As I mentioned before, normal healthy breathing

is breathing about six liters of air per minute.

But of course, most of us don't think

in terms of liters of air, and we're not

going to measure our lung capacity, at least most of us

aren't going to do that.

Basically, if you are taking relatively shallow breaths

and you're just sitting there working or maybe even walking

slowly, again, not talking or engaging

in any kind of speech or eating, chances

are six liters of air per minute is about 12 shallowish breaths.

And when I say shallow, I don't mean

breathing [INHALES SHALLOWLY] like a little bunny

rabbit or something like that.

I just mean casually breathing in out, in out.

The studies that have explored the breathing patterns

in large populations of individuals who are not

suffering necessarily from any one specific ailment

have shown that most people breathe far too much

per minute, that they're engaging

in anywhere from 15 to 20 or even 30

shallow breaths per minute.

So they are vastly overbreathing relative to how

they should be breathing.

Now, of course, if you breathe more deeply,

so you take a vigorous inhale [INHALES]

and then you expel that air, well,

then to get six liters of air into your system per minute,

you're probably only going to need somewhere between four

and six breaths in order to get that six liters per minute.

Now, the total time that it takes

to do that inhale and exhale isn't that much longer

than a shallow breath, provided you're not deliberately

breathing quickly during those shallow breaths.

So then you say, well, how is it that normal healthy breathing

that delivers the appropriate amount of carbon dioxide

into the system and doesn't expel,

doesn't exhale too much carbon dioxide--

how are we supposed to do that normal breathing?

Are you supposed to breathe four times

and then hold your breath until the minute passes?

No.

What you find is that the correct pattern of breathing

is going to involve two things.

First of all, nasal breathing, because of the resistance

it provides through the nose that we talked about earlier,

is going to deliver more oxygen into your system.

You're going to be able to generate more air

pressure to fill your lungs.

That greater air pressure is going to take longer to exhale.

So already we're increasing the amount of time

that each breath is going to take.

And also what you find is that people that

are breathing in the proper healthy manner, that is,

that are balancing oxygen and carbon

dioxide in the proper ways, are also

taking pauses between breaths.

This is extremely important.

Because even though we have a brain center,

the pre-Botzinger complex, that can control or, I should say,

does control inhale-exhale rhythmic breathing,

those pauses between breaths are not always present

and, in fact, often are not present

from people's baseline breathing patterns.

As a consequence, they overbreathe.

And as I told you before, when people overbreathe,

their brain becomes hyperexcitable

at the level of the background noise.

And yet they are less efficient at detecting and learning

information.

We'll get into the specific studies

that really illustrate the learning aspect a bit later.

But they are less efficient at detecting and learning

information, at focusing, and so on as a consequence

of this overbreathing and the hyperexcitability

that it causes.

Now, of course, that's also just emphasizing

the effects of overbreathing and lack

of carbon dioxide on the brain.

There are hundreds, if not thousands

of studies showing that when we don't have enough carbon

dioxide in the tissues of our body,

that's also problematic for all the tissues-- the liver,

the lungs themselves, the stomach, et cetera-- that

relate largely to shifts in pH because of the fact

that carbon dioxide strongly regulates

the acidity, alkalinity of the blood and the tissues

that that blood supplies nutrients to,

including carbon dioxide.

So the basic takeaway here is you

want to breathe in a healthy manner at rest.

And the best way to do that is to spend some time--

and it doesn't take much, maybe a minute or so each day--

paying attention to how quickly you are breathing per minute

when you are simply at rest, when you're making coffee

in the morning, when you're sitting down to read,

when you're on social media.

Chronically holding your breath isn't good

but neither is overbreathing.

And, again, every study that has examined the typical patterns

of breathing and patterns of breathing

that show up as normal and abnormal

has found that more often than not,

during the nighttime, people are underbreathing.

And in the daytime, they are overbreathing.

They're hyperventilating.

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So next, I'd like to address what

you can do about your normal patterns of breathing,

that is, how you or anyone can adjust

their normal patterns of breathing from an unhealthy

to an unhealthy state.

But the first thing we have to do, of course,

is determine whether or not you're already

breathing in an unhealthy or in a healthy way.

And, again, when I say healthy or unhealthy, I mean,

are you overbreathing?

Are you underbreathing?

Are you delivering the appropriate ratios

of oxygen and carbon dioxide to the tissues

of your brain and body?

In order to do this, we're going to do a simple test.

Again, please don't do this while

driving or operating heavy machinery or near water

of any kind.

But assuming that you're not doing any of those things,

I encourage you to sit down, certainly

not lie down but just sit down.

I suppose you also could do it standing.

And we are going to do what's called the carbon dioxide

tolerance test.

The carbon dioxide tolerance test

is a sort of back of the envelope

measure of how well you are managing carbon dioxide,

that is, how well you can control your breathing

at both the mechanical and the chemical level.

It's a very simple test.

What you're going to do is for the next 10 seconds

or so while I'm speaking, you're just going to breathe normally.

Now, again and again throughout this episode,

I'm going to encourage you to be a nasal breather whenever

possible.

But of course, there are instances in which you

want to engage mouth breathing.

But for the time being, as I continue

to blab on for the next few seconds,

just inhale through your nose, exhale through your nose.

You don't have to deliberately slow your breathing

or increase the cadence of your breathing.

However, in that time, you're also

going to want to find some sort of time measuring

device, like could be your phone or it could be a stopwatch.

What I'm going to ask you to do in a few minutes

is I'm going to ask you to inhale through your nose

as deeply as you possibly can.

That is, you're going to fill your lungs as much as you

can through your nose.

And then start a timer and measure

how long it takes for you to deliberately control

that exhale until your lungs are empty.

So this is going to be a controlled exhale

through the nose after a big deep breath.

But for the time being, keep breathing

at a kind of calm, regular cadence.

So you can find that time measuring device now,

or you can come back to it later if you like.

When I say inhale, you're going to inhale as deeply as you can

through your nose, remembering that the diaphragm can really

help you here to get a deep inhale by having

your belly move out while you inhale.

And then when I say start, you're

going to measure the time that it takes to do

a complete lungs empty exhale.

In fact, I'll measure it for you.

This will be one of the rare instances in this podcast

where there's going to be a long period of silence

as I measure something.

So I've got a stopwatch here.

So please prepare to do the big inhale and start inhaling now.

So inhale as deeply as you can through your nose.

Fill your lungs as much as you can.

OK?

Now start, meaning slowly control the exhale

through your nose.

You're trying to let that air out as slowly as possible.

And I'm just going to call out every 10 or 15 seconds or so.

And you want to note when your lungs are empty.

I know you can hold your breath with your lungs empty.

That is not an accurate measure.

15 seconds.

It is important that when note your lungs are empty

and that you're trying to control the exhale as much

as possible so that you don't arrive at that lungs empty time

too quickly.

I'll explain what too quickly means.

30 seconds.

OK, for those of you that have already reached lungs empty,

please go back to breathing normally.

For those of you that haven't, you

can hang in here a little longer if you're still

discarding that air.

45 seconds.

And we're rounding toward a minute, not quite there.

Some of you are probably still letting out that air.

I want to point out none of this has

to do with cardiovascular fitness level, at least

not in any kind of direct way.

And 60 seconds.

And I realize there will be a small subset of you

out there that are still expelling

your air in a slow lungs--

slow exhale manner through the nose.

OK, so what we just did is a back of the envelope carbon

dioxide discard rate if you need to pause this

and go back and try it again you just

want to time how long it takes you

to go from lungs full to lungs empty, again,

with the full understanding I know that you can all sit there

like beasts and hold your breath with your lungs empty.

But please don't do that because that's not going

has been informative for what I'm telling you now.

What I'm going to tell you now is

that if it took you 20 seconds or less to expel all your air,

that is, you couldn't extend that exhale longer

than 20 seconds, in a kind of back of the envelope way,

we can say that have a relatively brief or low carbon

dioxide tolerance.

If it took you somewhere between 25 and 40, maybe 45 seconds

to expel all your air, that is, you

could control that exhale for about 45 seconds or 30 seconds,

then you have a moderate level of carbon dioxide tolerance.

And if, for instance, you were able to go 50 seconds

or longer for that discard until you hit lungs empty,

you have a fairly high degree of carbon dioxide tolerance.

Now, here's the deal.

If you had low carbon dioxide tolerance, that

is, you're 20 seconds or less, you're

going to write down the number three.

If you had moderate levels of carbon dioxide tolerance,

you're going to write down the number five.

or you could even put five to six.

And then if you are in that bracket of people

that was able to discard your air over a period of 50 seconds

or more, you're going to write down the number 8 to 10.

OK?

Now, what are these numbers?

What are we talking about?

And before we get into what to do with these numbers,

I want to emphasize again, this does not

have to do with fitness level per se.

I know some world class triathletes

that have very fast carbon dioxide blow-off times.

That is, their discard rates are 20 seconds or less.

I should also point out that if you're very stressed,

that number is going to be very small.

If you're very relaxed, like you just woke up

after a long night of sleep and you feel great,

that number is going to be extended.

So this is a back of the envelope measure

that you're going to use each time you

decide to do the exercise I'm going

to tell you about in a moment.

And the exercise I'm going to tell you about in a moment

can be done every day if you like.

But what the most interesting studies, at least to me,

indicate is that you could do the exercise

I'll tell you about even just once or twice a week

and greatly improve your efficiency of breathing

and shift yourself away from overbreathing when at rest,

even if you're not thinking about how

you're breathing at rest.

So what is this exercise?

Well, you just got your number, either low, medium, or high

bracket number for carbon dioxide discard rate.

Remember, if you're in the low category, your number is three.

If you're medium, it's five to six.

And if you are in the long carbon dioxide

discard rate, long duration carbon

dioxide discard rate, that is, 8 to 10 is your number.

Now you're going to do two minutes of what most people

would call box breathing.

What is box breathing?

Box breathing are equal duration inhale, hold,

exhale, hold, repeat.

So inhale, hold, exhale, hold.

Sounds very easy, right?

How long do you inhale and then hold, exhale and then hold?

Well, you now know.

If you are in the low group of carbon dioxide discard rate,

your inhale is going to be three seconds, your hold will

be three seconds, your exhale will be three seconds,

and then you repeat, three seconds.

So each side of the box, if you will,

is going to be three seconds long.

If you were in the moderate carbon dioxide discard rate

category, then you're going to inhale for five to six seconds,

hold for five to six, exhale for five to six,

hold for five to six, repeat for about two minutes.

You could do three minutes if you want.

But I think it's important to have protocols that

are feasible for most people.

And that's going to mean doing things for about two

to five minutes when it comes to these breath rehabilitation

exercises for restoring normal breathing.

And then, of course, if you are in the long category of carbon

dioxide discard rate, you should be able to do an 8 to 10

second inhale, 8 to 10 second hold, 8 to 10 second exhale, 8

to 10 second hold, and repeat.

So you could do that exercise now

if you like, or you could do it at some point offline.

You can pause this podcast if you want and go try it.

That's an exercise that you can do

for about two to three minutes once or twice per week.

What's happening when you do that exercise?

Well, first of all, you are greatly

increasing your neuromechanical control over the diaphragm.

This is very important.

Most people are not aware of this phrenic nerve

pathway in the diaphragm.

And you are greatly increasing your mechanical control

over this pathway through the process

we call neuroplasticity.

When you deliberately focus on a aspect of your nervous system

control and particular nervous system control over musculature

that normally is subconscious and you're not paying attention

to and when you actively take control of that,

it requires that your brain adjust and rewire

the relationship between the different components

of that circuit.

And the wonderful thing is that has

been shown to lead to changes in your resting pattern

of breathing.

Now, why did we go through the whole business

of doing the carbon dioxide tolerance test?

Well, for people who don't tolerate carbon dioxide very

well, they don't have very good phrenic,

that is, neuromechanical control of the diaphragm,

for whatever reason-- again, it doesn't mean you're not fit.

It just means you don't have or you have not yet developed

neuromechanical control of the diaphragm.

It would be near impossible for you

to do box breathing for two or three minutes with eight

seconds in, eight seconds hold, eight seconds exhale,

eight second hold.

So that's why we do a test to see

what you're capable of doing.

You don't want the box breathing to be too strained where you're

[GRUNTS],, where you're really challenged

to get around the whole box.

You want it to be relatively easy because, remember,

you're trying to translate this pattern to your normal pattern

of breathing, that is, your pattern of breathing

when you're not consciously thinking about breathing.

And what are we really translating

when we do this box breathing type exercise?

What you're translating is the ability

to pause between breaths and yet take

full mechanically-driven breaths that involve the phrenic nerve

and diaphragm.

So, again, you're encouraging, especially

if you use nasal breathing when you do the box breathing--

you're encouraging phrenic control over the diaphragm.

And you're getting that six liters of air per minute

or so using fewer and fewer breaths over time.

So this is a, again, zero cost-- although it

does cost a little bit of time-- zero cost approach

to adjusting your normal pattern of breathing at rest, which

has a huge number of positive outcomes in terms

of your ability to stay relatively calm, to not

get the hyperexcitability of the brain.

It has actually been shown in various studies--

and we'll talk about one in particular later--

to greatly improve not just levels of calm

and reduce bouts of stress but also improve nighttime sleep.

There are huge number of benefits

that can come from doing this box breathing exercise.

But you got to get the duration of the size of the box right,

and that's why you do the carbon dioxide tolerance test.

One thing that many people notice

after doing the carbon dioxide tolerance test even just once

and then doing this box breathing exercise once

or twice a week is that after two or three weeks, the box

breathing itself becomes very easy.

And in that case, I recommend taking the carbon dioxide

tolerance test over again.

And almost always what you'll find

is that you have been able to extend your carbon

dioxide discard rate, and therefore, you now

fall into a different category, not just the lower medium

but the long carbon dioxide discard rate category,

and you are able to extend the duration of those inhale,

hold, exhale, holds during the box breathing.

And, of course, the ultimate benefit of all this

is that it translates to deeper and yet less frequent

breathing when at rest and when not consciously paying

attention to how you're breathing during the daytime.

Again, if at all possible, do all of this breathing

through the nose.

For those of you that have a severely occluded nose,

the recommendation always is to breathe through your nose more.

But I do realize that for some people,

it's really uncomfortable to breathe through the nose

because they have such an occluded nasal pathway.

And for you folks, doing some of this breathing

through the mouth can probably suffice.

But if at all possible, do the breathing through the nose.

And please also let me know how your progress evolves over time

with the carbon dioxide discard rate and the box breathing.

And of course, the positive shifts

that occur in normal unconscious daytime breathing

translate to all the opposite things

that we talked about when you are overbreathing

during the daytime.

So what I just described in terms of the carbon dioxide

tolerance test and the exercise using box breathing

to restore normal patterns of breathing

and not overbreathe and therefore not eliminate

too much carbon dioxide is exactly

the two tests that were incorporated into a study

that my laboratory did in collaboration

with our associate chair of psychiatry

at Stanford School of Medicine, Dr. David Spiegel, who's

also been a guest on this podcast previously.

And that study explored box breathing.

But it also explored other forms of breathing

and actually compared those forms of deliberate breathing

to meditation as a means to explore

what are going to be the minimal effective doses and most

effective ways to chronically reduce stress around the clock

and improve mood and improve sleep.

So the study I'm referring to was just published recently.

It's entitled "Brief Structured Respiration Practices Enhance

Mood and Reduce Physiological Arousal."

We will also provide a link to this paper in the show note

captions.

What this study really focused on

was a simple question, which is, what is the shortest and most

effective practice that people can use in order

to reduce their levels of stress not just during that breathwork

practice or meditation practice but around the clock, 24

hours a day, including improvements in sleep?

And we were excited to do this study because many studies had

explored how meditation or, in some cases,

fewer studies have explored how breathwork

can impact different brain states or bodily states.

But very few studies had explored how those breathwork

or meditation practices influenced body-brain states

around the clock when people were not

performing the particular meditation or breathwork

practice.

The reason we were able to do this study

was really fortunate.

The folks over at WHOOP were generous enough

to donate a bunch of WHOOP straps, which

allowed us to measure heart rate variability,

a number of other different physiological parameters.

We also got subjective reports about people's mood

and feelings of well-being.

We got data about their sleep pinged to us

from remote locations.

So these people, rather than being brought to the laboratory

and being in a very artificial circumstance, the laboratory,

as much as we like to think our laboratory

is realistic-- we have virtual reality

and things like that-- there's nothing

as realistic as the real world.

And so we were able to have more than a

hundred subjects out in the real world living their real lives

pinging back to us data all the time, 24 hours a day

so that we could measure how their different interventions

that we asked them to do, breathwork practices

or meditation practices, were impacting

physiological parameters.

And they were also informing us regularly

about their subjective mood, et cetera.

We got a lot of data, as you can imagine.

And the basic takeaway from the study was twofold.

First of all, we discovered that deliberate breathwork practices

done for about five minutes per day

across the course of about a month led

to greater reductions in stress than did a five minute a day

meditation practice.

Now, that is not to say that meditation is not useful.

In fact, there are dozens, if not hundreds, of papers,

including one particular, I should

say, particularly beautiful study from Wendy Suzuki's lab

at New York University showing that a daily 10 to 13 minute

mindfulness meditation practice can greatly improve focus,

memory, and a number of other things related to cognition

and learning.

However, the research on meditation

has shown us that meditation, at least short meditations,

mainly lead to improvements in focus and memory,

not so much reductions in stress, although they do

lead to reductions in stress.

What we found was that any number of different breathwork

practices-- and we explored three--

done for five minutes a day outperformed meditation

in terms of the ability of breathwork

to reduce stress around the clock compared to meditation.

The three types of breathwork that we explored also

showed different effects.

I should mention the three types of breathwork

that we compared were box breathing of the sort

that you just learned about.

We compare that to something called cyclic sighing, which

involves two inhales through the nose

to get maximally inflated lungs followed by a long exhale.

I'll return to that in a moment.

That was repeated for five minutes

at a time for each session.

And a third breathwork practice, which

was cyclic hyperventilation, which, as the name suggests,

involves people inhaling deeply through the nose,

then exhaling passively through the mouth,

and then repeating inhale through the nose,

exhale through the mouth, repeating

that for 25 cycles, one cycle being an inhale and an exhale.

So that equals one cycle.

Repeating that for 25 cycles, then exhaling all their air

and holding their breath with lungs

empty for about 15 to 30 seconds,

and then repeating inhale, exhale, cyclic hyperventilation

for the duration of five minutes.

So people were divided into these different groups,

either mindfulness meditation where they sat,

they were not told to control their breathing

in any specific way.

They closed their eyes.

They focused their attention on a region

just behind their forehead.

One group did that.

The other group did cyclic sighing.

Another group did box breathing.

Another group did cyclic hyperventilation.

As any sort of clinical trial like this ought to,

we then swapped people into different groups.

So they served as their own control.

So we could evaluate any between and within

individual variability.

Again, there are a lot of data in this paper.

But the takeaway was that for the sake of stress reduction

around the clock and for the sake of improving sleep

and mood, the most effective practice

of the four practices that we examined

was the cyclic sighing.

Again, cyclic sighing is performed the following way.

You inhale through the nose as deeply as you can.

Then you do a second inhale immediately afterwards to try

and maximally inflate the lungs.

In fact, that's what happens.

We know that during that second inhale,

even if it's just a very sharp, short inhale,

the extra physical vigor that's required

to generate that second inhale causes

those alveoli of the lungs, which may have collapsed--

and, indeed, in between breaths and often even just

through the course of the day and especially

if we get stressed, those alveoli of the lungs

start to collapse.

And because they're damp on the inside--

they have a little bit of fluid.

They're like a balloon with a little bit

of fluid in the middle.

It takes a little bit of physical force

to pop those open.

Now, you're not literally exploding them pop.

But you're reinflating them with air.

And then you perform the long exhale through the mouth

until lungs are empty.

So it looks exactly like this.

[INHALES DEEPLY]

[INHALES SHARPLY]

[EXHALES]

Now, we know that one single physiological sigh

of the sort that I just described

performed at any time of day under any conditions,

whether or not you're about to walk on stage to give a talk

or you're in a meeting and you're feeling stressed,

or you're in a conversation that's very stressful,

or you can feel stress mounting because you're in traffic

or any number of psychological or physical stressors

that may be approaching you or you feel

are oppressing you, doing one physiological sigh of the sort

that I just described is the fastest physiologically

verified way that we are aware of to reduce

your levels of stress and to reintroduce calm, that is,

to shift your autonomic nervous system

from a state of heightened levels of autonomic arousal.

That is, sympathetic nervous system as, it's called,

is at a higher activation level than the so-called

parasympathetic nervous system.

Again, sympathetic nervous system having nothing

to do with sympathy, has everything

to do with so-called fight or flight,

although it controls other things,

too, including positive arousal.

And the parasympathetic nervous system,

often referred to as the rest and digest system,

although it does other things, too,

is associated with calming.

Those two things are always in kind

of push-pull with one another, like a seesaw or push-pull,

however you want to think about it.

One physiological sigh, meaning that big, deep inhale,

short second inhale also through the nose,

and then long exhale to completely lungs empty,

is known to restore the level of balance

in the sympathetic-parasympathetic

neural circuitry and is the fastest way

to reintroduce calm.

That's one physiological sigh.

In this study, what we asked was that people

perform that repeatedly, so-called cyclic sighing,

for the duration of five minutes.

And the people who did that cyclic sighing

for five minutes a day, regardless of the time of day

that they did it, experienced the greatest reductions

in stress not just during the practice

but around the 24-hour cycle.

And it translated, again, to all sorts

of positive subjective changes-- improvements in sleep, lower

resting heart rate at all times of day.

So this is important.

Again, this study was not just exploring

what happens during meditation or breathwork,

cyclic sighing, et cetera.

It was exploring how the changes that occur during that practice

translate to changes in breathing

and heart rate, mood, et cetera, throughout the 24-hour cycle.

So the takeaway here is twofold.

First of all, if you are somebody

who wants to improve your mood and reduce

your overall levels of stress and you only

have five minutes a day to invest in that,

hopefully you're doing all the other things

like trying to get proper sleep and exercise,

social connection, nutrition, et cetera, sunlight

in the morning, of course.

Can't leave that out.

But if you were going to devote five minutes a day

to a stress reduction practice that is now supported

by data to translate to reductions in stress

around the clock, the data say that you

would want to invest that in cyclic sighing, that is,

double inhale through the nose, extended exhale

through the mouth until your lungs are empty,

then repeat for five minutes a day.

You, of course, if you like, could do meditation.

It still had positive effects, meaning

it reduced stress, although not as much as cyclic sighing.

You could do box breathing if you

want for the purpose of reducing stress.

All the practices we explored did reduce stress.

But cyclic sighing performed for five minutes a day

had the most robust and pervasive effect

in reducing stress, improving mood, and improving sleep.

That's the first message of the study.

The second takeaway is that one physiological sigh--

that's right just one physiological sigh, where

you inhale deeply through the nose

another inhale through the nose to maximally inflate

the alveoli of the lungs, and then you

exhale to completely lungs empty and then go back

to normal breathing, is the fastest

way to introduce a level of calm and to reduce

your overall levels of stress in real time.

And this is very important.

I think that out there these days,

we hear a lot about stress reduction techniques.

And most all of the stress reduction techniques

that have been explored, everything

from massage to meditation to breathwork to a hot shower

to a foot rub, will calm you down.

The question is, do they calm you down just

during that practice?

Great if it does.

But does it also translate to reduced levels

of stress at other times in the 24-hour cycle

and other positive effects as well?

So one physiological sigh is a very efficient way

to adjust that ratio of sympathetic to parasympathetic

activation and immediately bring about calm.

So it's excellent for real-time control of stress.

The other thing about physiological sighs

is that it's not a hack.

It's not the application of a breathing practice to something

that it wasn't intended for.

In fact, physiological sighs were not

discovered by me at all.

They were discovered by physiologists

in the 1930s, who found that when people underbreathe,

they have a buildup of carbon dioxide in their system.

And even though carbon dioxide is essential for life,

you don't want too much of it in your system.

And that people, whether or not they were asleep or awake,

would engage a physiological sigh spontaneously,

subconsciously.

They would do this double inhale through the nose

and extended exhale through the mouth.

And that did not just eliminate excessive carbon dioxide

from the system.

It also rebalanced the oxygen-carbon dioxide ratio

in the proper ways.

In fact, it's observed in animals.

You might see this in animals that are tired.

When animals or humans get tired,

they tend to start underbreathing a little bit,

and that can often disrupt the balance of carbon dioxide

and oxygen. And right before a dog will go down

for a nap, for instance, you'll notice that it'll

do this double inhale, exhale.

people when they are sleeping, if they hold their breath

for a period of time, which, frankly, all of us

do periodically throughout sleep,

they will engage a spontaneous physiological sigh.

During the daytime, we are often holding our breath, especially

nowadays-- and there's a study on this

that we'll talk about a little bit later-- where

when people text message or they're emailing,

although nowadays people are mainly on social media and text

messaging, they often are holding their breath.

They will follow a breath hold by a physiological sigh

because during that breath hold, they're

building up the level of carbon dioxide in their system.

Now, mind you, I spent close to a half an hour

telling you that most people are overbreathing at rest,

and that's also true.

But people often will shift from overbreathing

to underbreathing, which is a terrible pattern.

So physiological sighs done either as a one-off, one

physiological sigh to clamp stress or reduce stress

in real time, or repeatedly over five minutes as a practice

that you do each day is going to be not just the most

effective way to approach reducing stress

around the clock and in real time but also the one that's

highly compatible with the way that the neural circuits

that control breathing were designed.

The physiological sigh has some other very useful applications.

One of the more, I would say, useful ones, at least to those

of you that exercise, is going to be

the use of physiological sigh in order

to remove the so-called side stitch.

So if you've ever been running or swimming or exercising

and you felt a cramp on your right side,

chances are, despite what your high school PE coach told you,

that raising your arms above your head

or drinking less water before you exercise

is not going to get rid of that cramp.

And here's why.

It's not a cramp at all.

If you recall the cervical 3, 4, and 5 nerves that

give rise to the phrenic nerve and go down and innervate

your diaphragm, well, as I mentioned before,

a certain number of those nerve fibers

actually course into the diaphragm and go up underneath.

And if you recall earlier, I also

said that the diaphragm sits right on top of the liver.

In other words, you actually have a sensory innervation

of the diaphragm, the deep diaphragm, and the liver.

And there's something called referenced pain, which

is what people generally experience

when they have that side stitch on their right-hand side.

So if you're ever exercising and you

feel a cramp on your right-hand side,

it's possible that it's a genuine cramp.

But more likely is the fact that that phrenic nerve

sensory innervation is now being carried up to your brain

and you are detecting some local or referenced pain in the liver

and in the diaphragm.

Now, that doesn't necessarily mean

you're doing anything wrong, although you might not

be breathing properly for running at that moment,

and that's what gave rise to it.

It could be some spasming of the phrenic nerve

or some inefficient breathing during running.

We had an entire series on fitness with Dr. Andy Galpin.

One of those episodes included a lot of information

on breathing.

It was the episode on endurance, although breathing

was a topic that was thread through multiple episodes

in that series.

You can find that series at HubermanLab.com.

Talks a lot about how to breathe during running,

how to breathe during weightlifting, et cetera.

But the point for now is that if ever you're

experiencing that right-side side stitch,

I encourage you to perform the physiological sigh.

And the good news is you can perform it while still running

or while still swimming, although I

suppose with swimming, you might have

to make some adjustments because, of course,

you don't want to inhale water, or while cycling

or any type of activity.

If you perform that physiological sigh generally

two or three times, what will occur

is that because of changes in the firing

of the phrenic nerve, and in particular because of changes

in the sensory feedback from the sensory component

of the phrenic nerve back to the brain,

you will experience an alleviation of the pain

from that right-side side stitch.

In other words, you can get rid of side cramps

doing physiological sighs during activities,

in particular during running activities.

Now, I should also mention that if you're experiencing a side

stitch on the left-side, chances are

that has to do with excessive air or fluid in your stomach.

And there are reasons for that that

also have to do with the way that the phrenic nerve is--

it's bilateral and branches to both sides

and is catching sensory input on the left side from some

of the local organs and sensory innervation of those organs.

But if you have right-side side stitch,

the physiological sigh done two or three

times while still running ought to relieve that side stitch.

Now, as long as we're talking about breathing

and the phrenic nerve and the relationship

between the phrenic nerve and your liver and your stomach

and some of the other organs in that neighborhood,

we should talk about the relationship between breathing

and heart rate.

This is an incredibly important topic,

so much so that I perhaps should have brought it up

at the beginning of the episode.

But nonetheless, you now know what your diaphragm does.

When you inhale, your diaphragm moves down.

That's right.

When you contract your diaphragm, it moves down.

It creates space for your lungs to inhale.

And when you exhale, your diaphragm moves up.

Well, when you inhale and your diaphragm moves down,

what happens is there's more space created

in the thoracic cavity and particularly if you're also

breathing deeply and you're using those intercostal muscles

to expand your ribs.

As a consequence, the heart actually

gets a little bit bigger.

It's a temporary enlargement in the heart.

But it's a real enlargement.

And as a consequence, whatever blood is in the heart

is now in a larger volume because the heart got bigger.

And as a consequence, that blood is moving more slowly

through that larger volume for a short period of time.

But nonetheless, it's moving more slowly.

Your nervous system detects that and sends a neural signal

to the heart to speed the heart rate up.

In other words, inhales increase heart rate.

The opposite is true when you exhale.

When you exhale, your diaphragm moves up.

Your rib cage tends to move inward a bit.

And you compact the heart.

You reduce the volume of the heart overall.

When you reduce the volume of the heart overall,

blood flow through the heart accelerates

because it's a smaller volume.

So a given unit of blood is going

to move more quickly through that small volume.

Your nervous system detects that and sends a signal

to slow the heart down.

So just as inhales speed the heart up,

exhales slow your heart rate down.

Now, of course, even though you can double up on inhales

or even triple up on inhales, sooner or later, if you inhale,

you're going to have to exhale.

And the converse is also true, of course.

So what does this mean in terms of controlling your heart rate?

Well, let's say you are going in for a blood draw,

or you're going out on stage and you're stressed.

Well, I would encourage you to do a physiological sigh, maybe

two physiological sighs to bring your level of calm up

and your level of stress down.

Nonetheless, if you have any reason

why you want to quickly reduce your heart rate

or accelerate your heart rate for sake of physical work

output or to calm yourself down additionally, not just use

the physiological sigh, well, then you

can take advantage of this relationship between inhales

and exhales controlling heart rate.

If you want to increase your heart rate,

you can simply inhale longer and more vigorously

relative to your exhales.

And if you want to decrease your heart rate,

well, then you're going to make your exhales longer

and/or more vigorous than your inhales.

In fact, this process, which is called respiratory sinus

arrhythmia, is the basis of what we call heart rate variability.

Heart rate variability involves the vagus nerve,

the 10th cranial nerve, which is a parasympathetic nerve that

is associated with a calming aspect

of the autonomic nervous system, slowing your heart rate down

by extending your exhales.

And it really forms the basis of most all breathing practices.

If you look at any breathing practices,

whether or not it's Wim Hof breathing, Tummo breathing,

Kundalini breathing, Pranayama breathing,

physiological sighing, cyclic sighing, and on and on and on,

if you were to measure the ratio of inhales to exhales

and the vigor of inhales to exhales, what you would find

is that each one would create a net increase or a net decrease

in heart rate that could be very accurately predicted by whether

or not that breathing practice emphasized inhales, emphasized

exhales, or had those two features, inhale and exhale,

be of equal duration and intensity.

In fact, if you wanted to equilibrate your heart rate,

what you would do is you would do box breathing

because inhale, hold, exhale, hold

is, by definition, creating equal duration inhales

and exhales of essentially equivalent vigor.

When you do a physiological sigh,

you're doing two big inhales, which

is going the speed your heart rate up

just a little bit, but then a long extended exhale.

The exhale in the end is much longer than the two inhales

even when combined.

And so you get a net decrease in heart rate, the calming effect.

And then practices such as Tummo breathing or Wim Hof breathing

or cyclic hyperventilation, [HYPERVENTILATES] deep inhales

and exhales, the inhales are more vigorous compared

to the more passive exhales-- are

going to lead to increases in heart rate.

So the relationship between breathing and heart rate

is an absolutely lockstep one where your heart

rate follows your breathing.

Your heart rate and your breathing

are in an intimate discussion with one another,

but where always and forever your inhales

increase your heart rate, your exhales decrease it.

Now, this feature, which physicians

call respiratory sinus arrhythmia,

or we sometimes hear about more often nowadays as heart rate

variability, is something that people in sport

have known about for a very long time.

It's why, for instance, that marksmen will exhale just prior

to taking a shot.

That's particularly true for people

that compete in the biathlon, where they cross country ski.

So their heart rate is up, up, up, up, up.

Then they'll get to the point where they actually

have to shoot a target, and they'll exhale,

and then they'll shoot the target.

This is also why, for instance, if you want to bring your heart

rate down very quickly between rounds of martial arts,

there are a number of different ways to do that.

But an extended exhale of any kind or, frankly, any breathing

practice that emphasizes exhales is going

to bring your heart rate down.

This has been incorporated in a number of different contexts,

including sport, military.

It's also now being incorporated in a clinical context

for people who feel a panic attack coming on.

I'm very gratified to learn that the physiological sigh is now

being explored as a tool to prevent panic attacks

and anxiety attacks.

This is prior to the panic attack, people

bringing their heart rate down, again,

through those extended exhales.

So learning to extend your exhale

is really a terrific skill to master,

and it's a very easy skill to master, frankly.

Why do I say a skill?

Well, remember what I said earlier,

which is that humans inhale actively

and most typically will passively exhale,

just let the air [EXHALES] drop out of them at whatever rate,

depending on how much air they inhaled.

Actively exhaling, that is, actively relaxing the diaphragm

and actively relaxing those intercostal muscles

of the chest, those ones that are, I should say,

between the ribs, is a skill that you

can very quickly acquire and will

allow you to use that relationship

between the phrenic nerve, the diaphragm, and the size

of the heart, the heart volume, and all that stuff

to really take control of heart rate quickly.

So that if you feel like your heart is racing too much--

and, frankly, a lot of people have

a lot of what's called interoceptive awareness,

especially anxious people.

They can really sense what's going on

in their body, other people less so.

Like, oh my god, my heart's beating.

It's ready to jump out of my chest, and I don't like that.

I don't like that.

[EXHALES] Big, long exhale.

It doesn't matter if you do it through the nose or the mouth.

Big, long exhale is going to allow you

to slow your heart rate down.

Let's talk about hiccups.

Everybody experiences hiccups from time to time.

I think most people would agree that one hiccup is

sort of funny.

Two hiccups in a row is really funny.

And three hiccups in a row is where

it starts to be concerning, in part because hiccups

can be kind of painful.

You can experience pain in your gut or your lower abdomen

and sometimes in your chest as well.

And it feels kind of intrusive.

It gets in the way of having conversation or just

sitting there and relaxing.

Fortunately, there's a simple way to get rid of hiccups.

And you can arrive at that simple technique

if you understand a little bit about what

gives rise to hiccups.

The reason we get hiccups at all is

because we experience a spasm of the phrenic nerve.

The phrenic nerve, as you recall,

is a nerve that emanates from the cervical region,

to be specific C3, 4, and 5.

Those spinal nerves go down, of course, behind the heart

and innervate the diaphragm, which

is the muscle that when it contracts, it moves down

and allows the lungs to fill.

And then when you relax the diaphragm,

then the diaphragm moves up, and the lungs shrink

or they expel air, so-called exhalation.

Now, the phrenic nerve also has that sensory branch.

So it's not just involved in controlling the diaphragm

at the motor level.

It's also sensing things deep within the diaphragm

and in the liver as well because the liver sits right

below the diaphragm.

So a hiccup has that painful sensation from time

to time because there's a rapid sensory feedback

or a signal, rather, of a sharp sensation of contraction

within the diaphragm.

And that's relayed back to the brain.

And you consciously perceive that as a little bit of pain.

And then, of course, the hiccup is [HICCUPS] the hiccup,

which is the spasming of the phrenic nerve

that you experience more or less in your throat.

But all this really is happening along the phrenic nerve

and toward the diaphragm.

What this all means is that if you

can stop the phrenic nerve from spasming, you can stop hiccups.

There are a lot of approaches that people

have tried to take to eliminate spasming of the phrenic nerve.

You'll hear that breathing into a bag, which

is one way to reingest or reinhale carbon dioxide that

otherwise would be expelled out into the environment, can help.

That's a very indirect method.

It rarely works, frankly, because it really

has to do more with adjusting your breathing

to try and adjust the activity of the phrenic nerve.

It's a really roundabout way of trying to alleviate hiccups.

Some people will experience relief

from drinking from a glass of water

from the opposite side of the glass.

So you have to tilt over at the waist.

It's a kind of messy approach.

Again, it doesn't tend to work a lot of the time.

For some people, it works every time.

But for most people, it doesn't work at all.

However, there is a technique that

can reliably eliminate hiccups.

And it's a technique that takes advantage of hypercontracting

the phrenic nerve over a short period of time

so that it then subsequently relaxes or alleviates

the spasming of the phrenic nerve.

And that simple method is to inhale three times in a row.

This is a very unusual pattern of breathing.

But what it involves is taking a big, deep inhale

through your nose.

Then before you exhale any air, take a second inhale

through the nose, however brief that inhale might be,