AMA #13: Winter Months & Sickness, Wim Hof Breathing & Stressors

ANDREW HUBERMAN: Welcome to the Huberman Lab podcast

where we discuss science and science-based tools

for everyday life.

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I'm Andrew Huberman.

And I'm a professor of neurobiology and ophthalmology

at Stanford School of Medicine.

Today is an Ask Me Anything episode or AMA.

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So without further ado, let's get

to answering your questions.

The first question is about colds and flus.

And the question specifically is,

why is it that we get more colds and flus in the winter months?

Is it the temperature outside?

Is it the fact that people are spending more time indoors?

Or is it a myth that we get more colds and flus in the winter

months?

Well, the first thing is that the research very clearly

shows that in winter months there is a greater

prevalence of colds and flus.

Now, of course, the words, "in the winter months"

means many things.

For instance, in most areas of the world unless you

live directly near the equator, in the winter

months means that days are going to be shorter

and nights are longer than in the summer months.

In general, that's true.

It's of course, especially true if you

live very far from the equator.

So imagine somebody living up in Tromsø, Norway, which is

very close to the North Pole.

In winter, days are very, very short in Tromsø.

And conversely in the summer months,

days are very, very long in Tromsø Norway.

Now, Tromsø Norway represents an extreme of day length variation

according to time of year.

The closer you get to the equator,

the less variation there is in day length and therefore night

length across the year.

However, in most locations on Earth,

days will be significantly shorter by about an hour or two

at least for certain parts of the year.

And in general, shorter days correlate

with colder temperatures.

That's what's really important to know,

which is that shorter days generally correlate with colder

temperatures regardless of where you live on the planet Earth.

OK.

So in the winter months as we're calling it,

involves at least two things, shorter days, which means what?

It means less sunlight and either more artificial

light or more darkness depending on how much artificial light

you rely on.

It also means, as we mentioned, colder temperatures.

Colder temperatures, of course, doesn't necessarily

mean that you are exposed to those colder temperatures

because what's the third thing?

Shorter days and colder temperatures

outside mean that people are spending more time indoors.

So what the research clearly shows

is that one of the reasons, not the only, but one

of the reasons for the greater prevalence of colds and flus

in the short days a.k.a.

winter months of the year is that people

are spending more time indoors and therefore

at closer proximity, which raises a whole bunch of really

interesting questions that have been explored

in the peer reviewed research about proximity cold and flu

transmission.

There have been studies for instance

where people come into the laboratory who are suffering

from cold and flu and are sneezing, having them sneeze

at different proximity to other people,

obviously people are doing this under consent.

They're agreeing to participate in

these particular experiments.

And there does seem to be a very nice relationship

between physical distance between you,

the uninfected person, and the sneezing,

coughing, nose wiping, eye wiping,

we'll get into why I mentioned all of those things

in a moment, person that is suffering from the flu.

In other words, the closer you are

to somebody who's sneezing or coughing,

the higher probability that you will contract that cold or flu.

OK.

So we've already established two things.

First of all, physical proximity is a key variable

in terms of transmission of cold and flu.

And at some level that's a duh.

I mean, if you think about it, if you're in the next room

or down the hallway from or across the street

from somebody with a cold or flu,

you don't expect to contract that cold or flu from them.

Whereas if you're in the same vehicle

with them or you're sitting next to them on an airplane

or you are on the same bus or in the same classroom as them

and they are sneezing and coughing,

well, then, the probability that you would get that cold or flu

from them is increased.

That's just obvious.

But the studies that have explored the relationship

between physical proximity and transmission of cold and flu

have actually analyzed things down to the range of well,

if you're standing one foot apart

or you're standing three feet apart or six feet apart,

what's the probability that you will contract that cold or flu?

And it follows a very direct relationship

where the closer the proximity, the more likely

that you're going to contract the cold

or flu from that person.

And of course, anything like exchange of skin contact

or exchange of saliva because obviously in cases

of romantic relationships where people will kiss

or in familial relationships or friendships where people hug,

any contact also further increases the transmission

of cold and flu.

Not just from stuff emitted from the nasal passages

and from the mouth when people sneeze and cough,

but also when people wipe their eyes,

even when people wipe their skin because oftentimes they

have cold or flu virus on their skin.

It doesn't always survive terribly long on the skin.

But if they wipe their face or wipe their nose

or are using tissues and then don't

wash their hands thoroughly afterwards,

indeed they can transmit cold and flu simply

through handshake.

OK.

So for all you hypochondriacs out there,

I'm arming you with a lot of useful knowledge

that will justify staying away from people

who perhaps have cold and flu.

Now, this particular point about proximity and people

being indoors more during the winter months,

and that's why there's more cold and flu transmission,

raises a whole bunch of interesting questions,

and, in fact, protocols that I plan to cover in a Huberman Lab

podcast episode solely devoted to colds and flus

and how to avoid getting colds and flus.

But one brief mention or telegraph of what

I plan to cover in that episode is

that if people are telling you that they are sneezing

and coughing due to a cold or flu but that they are quote

unquote "not contagious" either because they

are early in the cold or flu or late in the cold or flu

and they have these theories or claims that oh, I'm

no longer contagious.

Keep in mind that any time someone is sneezing or coughing

they are in fact contagious.

So I'll get back to that in that full length

episode about colds and flus.

But I felt it was too important not

to mention right now that people's theories about when

they are quote unquote "contagious"

or "not contagious" are rarely substantiated

by the actual data.

The actual data point to the fact

that when people are sneezing and coughing,

if it's due to a cold or flu, they are still contagious.

OK.

So we've established that cold outside means people tend

to be indoors more which increases

physical proximity, which is one of the reasons

why there's more cold and flu transmission.

One of the other reasons why being indoors more

tends to increase cold and flu transmission

is that in the cold months of winter when people are indoors,

they tend to be not under air conditioning,

not at neutral temperatures, but rather they

tend to be in heated rooms.

And depending on the type of heating

that's used, but in general, due to all forms of heating,

the heated air tends to be drier air.

Now, this is a little bit counterintuitive

because if you ever go outside on a really cold winter day,

you will realize that the cold weather

outdoors is extremely dry.

You can almost quote unquote "feel the dryness of the air."

And if you can't quote unquote "feel the dryness of the air"

or imagine what that's like just imagine this,

think of yourself outdoors on a very cold winter

day taking a brisk walk.

Then think about yourself taking that same brisk walk

on a very humid summer day.

Humidity is, of course, the concentration

of water in the ambient environment, the air,

whereas the dryness is the lack of humidity.

And just that little simple GedankenNet or thought

experiment will remind you just how

dry the cold air is out of doors during the winter months.

Whereas indoors we're heating that air

and indeed the heating of that air does

have the property of drying the nasal and oral passages

but especially the nasal passages.

So another key reason why there's

more transmission of colds and flus in the winter months

is because people are spending more time indoors.

And oftentimes the way those indoor environments

are being heated is drying out the nasal passages.

And the nasal passages represent a primary site

of defense for viral infections like colds and flus

but also bacterial infections and fungal infections

for that matter.

Now, I've talked before on this podcast about the importance

of using nasal breathing under any conditions where

you don't have to breathe through your mouth.

So if you are not eating, if you're not speaking,

or if you're not exercising hard which by the way

oftentimes requires that you breathe through your mouth.

There's nothing wrong with breathing through your mouth

if you're exercising hard and you

need to breathe through your mouth

in order to bring in enough oxygen.

There are conditions under which that's entirely appropriate.

You can learn more about that in the podcast episode

I did all about breathing and breath work.

But for the most part it's best to be a nasal breather

except under the conditions I just mentioned.

Why?

Well, the nasal passages contain a number of physical barriers,

including the hairs within your nose.

I know that hairs in the nose, especially

if they are super numerous are not

considered aesthetically nice.

People will trim them, et cetera.

But those hairs in your nose actually

serve as a barrier toward infection.

This is well established.

The lining of the nose, the mucosal lining of the nose

contains a lot of things.

First of all, it acts as its own physical barrier

and physical trap for incoming viruses, fungal infections,

and bacterial infections.

They literally get trapped in the nasal passages.

And therefore can't enter deeper into your physiology.

And right now is not the time to go

into the whole anatomy and physiology

of the nasal passages.

But keep in mind if you saw the episode

that I did with Noam Sobel or you listen to the episode

that I did on olfaction, both of those episodes

highlight the fact that your brain sits not

far behind your nasal passages.

There's a bony barrier there called the cribriform plate,

and there are some other things as well,

but it's not far from your nostrils to your brain.

And it is not far from your nostrils

to the rest of your respiratory pathway, of course.

And so the hairs of your nostrils, the mucus itself,

and the microbiome, the trillions

of little micro bacteria that thrive

in the mucosal lining of your nasal passages actually

serve to protect against many of the incoming infections.

This is why it's so important to keep

the mucosal lining of your nasal passages thriving and intact.

How do you do that?

Well, one of the best ways to do that

is to make sure that the air that you're breathing

is sufficiently humidified.

So while there are many different claims out there

about how to avoid colds and flus,

as long as we're having a discussion about why there

are more colds and flus in the winter months

because indeed there are, it's worth

mentioning that if you suffer from colds and flus

and you're going to spend a lot of time

in particular indoor environment,

you might be wise to find a air humidifier, something that

brings more moisture into the air

that you're breathing especially at night while you're sleeping.

Now, that's not going to prevent the person in your environment

who happens to have a cold or flu

and is sneezing actively from transmitting that cold or flu.

But it will keep your nasal passages

and the rest of your respiratory pathways

as healthy as they can be and as resistant

as they can be to any colds or flues

that you might be fighting off.

And this is another key point, which

is regardless of whether or not it's

the winter months or the other months of the year,

all day long you're combating different types of infections.

Different types of viral, fungal,

and bacterial infections are bombarding your system

and your immune system counters that

both through physical and through neurochemical

and hormonal and pure immune mechanisms.

OK.

There's a whole discussion of this in the episode

that I did on the immune system.

We'll do more on this.

But keeping the air that you breathe especially

at night sufficiently humidified is one great way

to try and offset colds and flus that you might be combating

because you brought that cold or flu

home from work and your immune system needs to ward it off.

OK.

If you are having a hard time grasping

how it is that you could bring home a cold or flu

and then ward it off, do you have it?

Do you not have?

It is it sitting there trying to get into your system?

Or do you have it a little bit?

Well, this is some of the gray area

around cold and flu and viral transmission generally.

I mean, we don't know, for instance,

if you got a mild sniffle as opposed

to a really bad cold or flu whether or not

it would have been a really bad cold or flu,

had you slept less, had you not humidified your air better,

et cetera.

Probably it would be.

And if you've ever not slept well for a little bit

and you're sick, you experienced just how much worse

that sickness feels.

The symptoms of that sickness go from very mild to moderate

or from mild to moderate to very severe

when you are sleep deprived.

That said, it's also clear that some strains of the cold or flu

can be more mild than other strains of the cold or flu.

So this can be pretty nuanced.

And we'll go deeper into this in the episode

that I do on cold and flu and how to avoid cold and flu.

But nasal breathing whenever possible day and night time

is extremely important for encouraging the overall health

and resistance of your respiratory

pathways to incoming cold and flu and other types of viruses.

Similarly, humidifying the air that you breathe especially

at night but perhaps also during the day in your OFS environment

or home environment can also be very beneficial for warding off

colds and flus.

And if you'd like to read more about the nasal versus mouth

breathing components of colds or flus,

I'll just mention one paper now and again, I'll

go into this in more depth in the future episode on colds

and flus.

But I want to mention that this is a bidirectional effect,

meaning people who deliberately breathe through their nose

tend to get fewer colds and flus.

Also people who tend to breathe through their mouth

more tend to get more colds and flus.

Now, you might think that's the same thing or just

two sides of the same coin.

But actually it's not.

There's what we call a double dissociation whereby

if people are mouth breathers, they

are far more susceptible to colds and flus

and other types of respiratory illnesses.

I'll put a link to one particular paper

that I like a lot in the show note captions entitled

association of oral breathing with dental malocclusions

and general health in children.

This paper explores a lot of different things

about nasal versus mouth breathing all of which,

by the way point to the fact that

nasal breathing whenever possible is better for us

health wise, aesthetically, dental health wise

than is mouth breathing.

But one of the key components here and this is

why I bring it up in the context of this discussion

is quote "oral breathing is related to a significantly

higher prevalence of allergies and a significantly more likely

getting sick and taking medication for being sick."

OK.

So lots in this study, lots in related studies.

But nonetheless, being a nasal breather, humidifying your air,

paying attention to whether or not

you're indoors with people who are coughing and sneezing

because it's cold outside, all of those things

are going to be relevant perhaps keeping

a little bit of distance, maybe a lot of distance

from those people or encouraging them to wash their hands

after they wipe their nose.

Maybe even sending them to a little bit of not necessarily

isolation although that might be necessary

but keeping them at a distance.

I don't think it's too much to ask somebody

who's sick to not get you sick.

Personally I think that's the polite thing to try and do.

And there's actually not many things ruder

than someone who knows that they're

sick showing up to something because they didn't want

to miss that particular event and getting everybody else sick

frankly, that's my opinion.

I think that opinion is shared with many of you

out there as well.

Now, as I mentioned earlier, when it's cold outside,

the air tends to be drier.

Not always.

I mean, you could live in an environment that's

very cold and very rainy, obviously very rainy

is very humid.

It's maximum humidity if you think about it.

But if you are going to spend time out

of doors in cold days of winter, which by the way,

is a really good thing for other reasons,

I'll get into those reasons in a moment

because they relate directly to why there's

such a prevalence of colds and flus

because in general, people are not doing what

I'm about to tell you to do.

But there are two things to keep in mind if you're

going to be out of doors.

First of all, the things about proximity still hold.

There have been studies of people

who have colds and flus sneezing in indoor environments

versus outdoor environments and how much transmission there is.

Again, it boils down to proximity.

Yes, you can get a cold or flu from somebody sneezing out

of doors next to you just as well

as you can if they sneeze next to you

indoors There's a slightly higher probability that you'll

get it from them if they're sneezing at that same distance

but you're indoors as opposed to outdoors obviously sneezers,

coughers-- sneeze and cough in the other direction,

cover your mouth and nose.

If you don't have a tissue or something, we are told

and I subscribe to the idea that sneezing into your elbow

or coughing into your elbow is probably the next best

thing to not covering up at all, as opposed to into your hand,

which then you touch other things and yourself.

Anyway, without getting into the mechanics of sneezing

and coughing too deeply, if you're

going to be outside in the cold winter months

and you'd like to avoid getting colds and flus, when you run,

when you exercise, when you walk,

when you're in conversation, try to nasal breathe unless you

have to mouth breathe.

And if you can sense your nasal passages or your mouth

drying out because of that hard breathing,

and by the way exercise during the winter

months is still important.

So I'm not discouraging people from exercising outdoors

during the winter months as long as you can do it safely.

But if you feel those air passages drying out,

just be aware that when you take those dried out

air passages in doors and you're around other people that

might have colds and flus, you are

going to be more susceptible.

So that's cause for taking a hot shower, perhaps if you have

access to a steam room or humidifier,

and rehydrating those nasal and oral passages.

Now, if you're outside and running

and you're breathing hard and your nasal passages are drying

out, does that mean that you're more susceptible to colds

and flus that are just out in that environment

if no one else is around?

Chances are no.

However, what we were all told when

we were kids which is if you go outside and you get a chill,

it's a good idea when you come back inside

to take a hot shower or a hot bath

or if you have access to it a sauna to heat back up.

That's also true, why?

Well, it does seem that there's a relationship

between core body temperature and susceptibility

to cold and flu.

And this is something I'm going to go

deeply into in the episode on colds and flus.

Keep in mind that fevers that are the response to exposure

to a cold or flu or being full blown sick with a cold and flu

are an attempt of your immune system to heat up that virus

and destroy it.

Keep that in mind if you're considering

taking any medication to lower your fever, of course,

know that highly elevated body temperatures a.k.a. fever

can be very dangerous to the brain and body.

There's a fairly limited upper range

of temperatures that we can go into before we

start damaging ourselves.

But also keep in mind that fever is an adaptation designed

to destroy viruses.

So if you blunt the fever, you are actually

letting a cold or virus to proliferate

more readily than it would if you allowed

a slight fever to combat that.

OK.

So there's a whole discussion to be had there because obviously

you don't want people cooking their brains

due to elevated fever and not treating that fever.

But you also don't want to reduce your core body

temperature too much which raises the question of things

like cold plunges.

Should you be taking cold showers

and doing cold plunges in the winter months

when it's already cold and you're susceptible to colds

and maybe you're coming down with a cold,

should you do that?

Well, that segues into the next question

that I'm going to answer for this AMA, which relates

directly to cold exposure and so-called cyclic

hyperventilation breathing sometimes associated

with so-called Wim Hof breathing but other forms of deliberate

breathing as well.

And how specific forms of deliberate breathing and how

deliberate cold exposure can indeed

be used to offset or even prevent entirely infection

due to bacterial or viruses.

But if you're already coming down

with a bacterial or viral infection,

why cyclic hyperventilation breathing or why deliberate

cold exposure may actually be the worst thing

if you are already contracting or have contracted,

if you are contracting or have already contracted

a cold or virus.

So we'll answer that question next.

In the meantime, just know that yes, indeed in the winter

months you are more susceptible to colds and flus

because there's more of them going around.

We talked about some of the reasons why they're

going around, and some of the things

you can do to protect yourself against those colds and flus.

There are a bunch of other things

that you can do that are very valuable that will explore

in the full length episode on colds and flus

and how to avoid getting them.

And I'm hoping you all stay clear of colds

and flus these winter months.

And now you have some tools to try and reduce

the duration and severity of those colds and flus

should you get one.

Thank you for joining for the beginning

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