AMA #10: Benefits of Nature & “Grounding," Hearing Loss Research & Avoiding Altitude Sickness

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 nature,

in particular about the scientifically-supported

benefits of getting outdoors into nature.

The person asks about the role of sunlight,

the role of calming sounds, the role

of observing wildlife, of observing green colors,

and, quote, "other stuff."

And in fact, I'm glad that they asked about "other stuff"

because I get the question about the scientifically-supported

benefits of nature a lot.

I often also get the question about grounding.

For those of you that aren't familiar with what grounding

is, grounding is a practice of putting your feet on the Earth

directly with bare feet, oftentimes

into soil or on a lawn.

And it's a question that I seem to get more and more.

In fact, every week for quite a long while now, on social media

or elsewhere, somebody asks me about the scientific support

for this practice of grounding.

So obviously there's a lot of interest

in what the scientific research says about getting into nature

and putting one's feet on the ground,

a.k.a. grounding, and so on.

OK, so if I'm going to answer this question,

I first have to be very direct with you.

There is excellent, meaning dozens, if not

hundreds, of quality peer-reviewed studies which

support the value of getting sunlight in one's eyes,

in particular early in the day to set your circadian rhythm.

This is something that I've talked about extensively

on the Huberman Lab podcast and as a guest on other podcasts.

It's one of the first and, frankly, most important

items on the toolkit for sleep, which is a zero-cost toolkit

that you can access by going to hubermanlab.com,

going to the menu, going to Newsletter.

You can see it as a PDF there.

You don't have to sign up for the newsletter.

You can just access that toolkit for sleep.

And you'll notice that very close to the top of that list,

if not top of that list, is to get sunlight in your eyes

early in the day.

You don't have to see the sun cross the horizon.

If you can, that's great.

But if you wake up after the sun has already

risen, go outside, face the sun, blink

as necessary to protect your eyes,

but get some sunlight into your eyes

every single day or as often as you possibly can,

especially on overcast days.

That's an absolutely unequivocally

science-supported tool that will increase daytime mood, focus,

and alertness and will improve your nighttime sleep.

Viewing morning sunlight also has profoundly positive effects

on metabolism.

Now, those effects on metabolism could

be the direct effect of viewing sunlight or, more likely,

they are the indirect consequence

of getting better sleep at night.

So getting sunlight in your eyes early in the day

and ideally in the evening or late afternoon

before the sun sets is a very well supported protocol

that we know is beneficial for numerous aspects

of mental health, physical health, and performance.

And of course, sunlight and getting sunlight in one's eyes

does require that you get outside.

You simply will not derive the same benefits

from viewing sunlight if you try and do it

through a window or windshield or if you

look at a picture of a sun on a screen.

Forget it.

You are not going to set your circadian rhythm.

You are not going to derive all the positive effects

of sunlight by trying to get it from screens

or from looking at pictures of suns or something of that sort.

Now, if you are somebody that, for whatever reason--

seasonality, where you live on the planet, work schedule, et

cetera--

who cannot get sunlight in your eyes early in the day

on a consistent basis, well, then you might consider

purchasing a so-called SAD lamp, which is for seasonal affective

disorder, which is very bright light that you can look

at in the morning for usually about 5 to 10 minutes.

People will put it on their counter

while they make their morning coffee, eat their breakfast.

And that has also been shown to improve mood, focus,

and alertness and set one's circadian rhythm.

But it is not nearly as effective as getting sunlight

in your eyes.

Now, why am I talking about this practice

that I've already talked about extensively

on numerous podcasts before?

Well, because the question is about nature,

and sunlight is a key feature of our natural environment.

But the person is also asking about other features

of nature-- seeing green colors, or blue colors,

or running streams for that matter.

Well, here, too, we can ask, what does the scientific data

really say about things like going

near a waterfall, or a running stream, or being near an ocean?

And actually, this is quite interesting.

There is actually a peer-reviewed literature

on negative ionization, as it's called,

which is a pattern of ionization that's

present close to bodies of water and particular types of bodies

of water, such as waterfalls, running streams, et cetera.

There's actually a laboratory at Columbia University School

of Medicine that has published fairly extensively

on the health benefits of negative ionization

as it relates to setting circadian

rhythm and some other aspects of mental and physical health.

I intend to host the head of that laboratory

on the Huberman Lab podcast in the not too distant future.

For now, we can safely say this--

there does seem to be some positive health

benefits to placing oneself near bodies of water,

in particular moving bodies of water.

And of course, as is always the case when there's

a discovery about how the natural world can impact

health, there have been some technologies developed

to create negative patterns of ionization

within a home environment.

But as with viewing sunlight exposure

and comparing it to, say, SAD lamps,

the negative ionization machines that one can purchase and put

in their home environment have been shown in a few studies

to produce some positive health benefits.

But those positive effects in no way

reach the level of positive effects

that have been demonstrated in studies where people

are actually spending a dedicated

period of time outdoors as near a moving body of water.

So in thinking about nature, natural environments,

there's strong evidence for getting sunlight in one's eyes.

There is some evidence for being near moving bodies of water,

perhaps--

again, I really want to highlight perhaps--

because of negative ionization created by those moving

bodies of water.

There is far less evidence for sunlight simulators

or negative ionization machines used indoors.

And then the asker of this question also, quite correctly,

asked about things like calming sounds,

watching wildlife, green colors, et cetera.

And herein lies a really important point for everyone

to digest.

While, of course, answering a question

about the natural world or about health

requires that we first pose a hypothesis-- for those of you

that aren't familiar what a hypothesis is,

a hypothesis is a stated prediction.

So it's not a question.

A question would be something like,

is getting out into nature good for our health?

A scientific hypothesis is where one actually takes a stance.

For instance, you could take the stance

and make the hypothesis that getting out

into nature for 30 minutes per day, three days per week,

improves mood and nighttime sleep.

So that's a hypothesis that then one would go on

to design an experiment to test and then evaluate

the data from that experiment and compare it

to the hypothesis, either validating or negating

that hypothesis.

That's essentially how science is done.

There's a lot more to it, but that's essentially

the scientific method.

And while, of course, the scientific method

is a fabulously powerful tool, for some questions,

it is a less potent tool.

And the question of is getting out into nature

helpful for enhancing our mental and physical health is

the sort of question that while ideally you

could design a really well controlled study to address,

it's actually quite difficult to design such a study.

And here's why.

In order to perform a study that's very well controlled,

meaning where you can isolate individual variables--

like sunlight, like the sorts of color contrast that one sees

in a natural scene outdoors in a forest or near a river--

in order to address whether or not

the calming sounds or the presence of squirrels running

through your environment are the relevant factors,

it becomes incredibly difficult to try and isolate

individual variables, meaning as soon as you bring people

into the laboratory, yes, you have more control over which

variables, as they're called, you present them,

by bringing them into a room that essentially has

no art on the walls and then having them look

at a picture of a sun or looking at sunlight

or listening to soothing sounds or looking

at a picture of a forest, of course,

you're controlling the individual variables.

However, there is a sort of gestalt,

meaning a collective picture of being

in nature that brings together lots

of different elements-- the element of surprise,

for instance.

The other day I was out for a Sunday hike,

and that morning I saw a squirrel running

across my path, and it was interesting

because the squirrel had a pinecone in its mouth.

It had been chewed down to the cob.

And the squirrel was probably only about 7 or 8 inches long,

and the pine cone was probably about 9 or 10 inches long--

the cob of the pine cone, that is.

And the interesting thing is that the squirrel

was carrying it long ways from the tip of the cob.

And so I delighted in the fact that this little squirrel

was working so hard to carry this object through the woods.

And this object was literally longer than its own body

length, and it looked so dedicated in its running

across the path in order to do whatever it

would with that pine cone cob.

So something like that obviously stuck in my memory.

It delighted me.

And at the very same time, there were a number

of other things happening besides the presence

of that novel wildlife experience.

There was the sound of a stream.

There's the sunlight.

There's the color contrast everywhere.

I'm breathing fresh air because I

was far away from any cars or any civilization, in fact.

And so here's what we know.

There are dozens, if not hundreds,

of studies that show that if people get out

of doors into nature--

this could be parks.

This could be near a stream.

This could be an ocean, any number

of different natural environments.

And if they do that for anywhere from 10 to 30 minutes,

three to seven days per week, indeed there

are demonstrated significant reductions

in things like blood pressure, resting heart

rate, improvements in sleep, improvements in mood.

And so I think we can very reliably say that, yes,

or perhaps even absolutely yes, getting outside into nature

can enhance various aspects of mental health, physical health,

and thereby performance in different aspects of life.

However, when talking about the benefits

of getting into nature, we are talking about hundreds, if not

thousands, of variables, some of which we are aware of,

such as the presence of wildlife or sunlight or color contrast.

And then, of course, there are going

to be dozens, if not hundreds, maybe even

thousands of other variables that we're not even aware of.

Perhaps it's negative ionization.

Most people aren't measuring the ionization of the air

when they go out into nature.

But perhaps it's also the presence

of certain smells from the soils that are being broken down

and then they're changing the oxygenation state of the air

around you, the plants, et cetera.

Again, so many variables, that, frankly,

to try and isolate any one of those variables

in the laboratory seems not just artificial,

but I think that it actually would just

lead to a diminished sense of just how valuable nature is.

So while, of course, the Huberman Lab podcast

is a podcast where we always center

on science and science-related tools,

meaning protocols that are grounded

in quality peer-reviewed studies that have been subjected

to control conditions where some people are getting,

say, the drug treatment or taking the supplement

or doing a particular behavioral practice and other people

are not or doing some variant of those and dose response curves,

all of that stuff, when it comes to the question of

whether or not it's valuable to get out into nature,

I think it's a very straightforward yes.

Absolutely yes.

Get out into nature as often as you can and safely can,

of course.

I realize some of this is weather permitting.

People live in different areas.

Some people are in cities.

Some people are in deserts.

Some people are near the ocean.

But getting out into nature has been shown over and over again

to have numerous positive health effects.

And yet, unless we're talking about sunlight exposure

and isolating the variable of setting one's circadian

rhythm by viewing sunlight early in the day, all

of the other features of getting out into nature,

things like forest bathing--

this is a term coined from some, frankly, pretty nice studies

that were done in Japan in which people placed themselves

into forest-like environments for a certain period of time.

There were control groups where people were not

placed into those environments, and the people

that did this so-called forest bathing experienced

enhanced mental and physical health.

That brought on a practice of people who could not get out

of doors into forests bringing plants

into their home environment, which I think all of us

would agree look nice.

They often will add pleasant odors to the air,

and perhaps they do actually shift our mental and physical

health in significant ways.

I suppose it depends on how much you like plants,

how much you pay attention to them, and, of course,

how many plants there are.

But-- and I think this is a really important

"but" to emphasize--

while most all questions about tools and protocols

for enhancing health immediately lead me to say, ah,

this study or that study or, yes,

there's evidence or, no, there isn't evidence, when it comes

to questions about nature and grounding in particular,

I take the stance that this is a unique instance where

we know there are just so many benefits of getting out

into nature that trying to isolate

any one of those variables in a quality,

rigorous way within the laboratory

almost seems too artificial to really justify

the conclusions that arrive.

Now, I'm sure there are some of you out there who are aware--

and if you're not, I'll tell you-- there

are studies that have explored this practice

of so-called grounding.

They've had people come into the laboratory

and place their feet on soil that is contained within a box

or there are other studies where they actually

have people go out of doors and place their feet

onto the grass or the ground.

And there are a bunch of theories

as to how grounding could improve

one's mental and physical health that aren't just about getting

outside.

So the theories go that this has to do

with the exchange of electrons with the Earth

and the Earth's surface in particular.

There's been the argument made that shoes,

in particular shoes that have rubber soles,

may block some of this electron exchange

with the surface of the Earth.

There have been theories about the tactile--

that is, the touch sensation-- with the Earth being important.

Not a lot of science published in, let's just say,

blue ribbon journals, which is not

to diminish some of the journals that these have been published

in, but just to say that, again, there are so many variables

associated with a practice such as grounding that I'll simply

say, yes, please do get out of doors into nature.

I try every Sunday to do my zone 2 cardio by rucking or jogging

or hiking, often with other people

if I'm trying to be social with family or others.

But the point is getting out of doors

has myriad positive effects on mental health

and physical health.

And of course, when you're moving out of doors,

you're also getting that zone 2 cardio or other forms

of physical benefit by elevating your heart rate

or perhaps you could even do your resistance training out

of doors on other days.

Now, I also try to get out of doors other days of the week.

But oftentimes, I'm, by way of weather

or by way of other commitments, forced to be indoors,

on planes, here at the podcast studio

where certainly I'm indoors.

But I try and get out of doors at least a few minutes

each day for a morning stroll, looking at sunlight, et cetera.

So the long and short of this is, yes, there's

some evidence for grounding.

Is it super strong evidence?

No, it's not.

We don't really know what it is about placing one's feet

onto the Earth that is producing the positive effects that

were observed in those studies.

And those studies made some reasonable attempt

to isolate the variables and figure out whether or not

it was ion exchange with the Earth or the tactile,

meaning the touch sensation, of having

one's feet on the ground.

Frankly, I don't think there's enough quality science

to really draw any firm conclusions about that.

However, if you like the idea of grounding, by all means, do it.

In fact, if it feels good to you,

I recommend getting your morning sunlight out

of doors with your bare feet on the ground.

Or if you're like me, you put on your shoes,

and you take a walk most days.

Although, I've tried this practice of grounding,

and it feels pretty good, meaning

it feels nice to have my feet on the Earth,

provided I'm on clean soil or clean lawn.

Definitely don't do this at the dog park.

Hookworm is a real thing, by the way, folks.

So pay attention to the sorts of surfaces

that you're putting your feet onto.

But the question about whether or not nature

is valuable for our mental and physical health is an easy one.

It's an absolute yes.

But isolating the particular variables about nature

that are most beneficial, well, that's a much tougher question,

and it's one that, frankly, the scientific method is not

and, to be honest, I don't think ever

will be in a position to isolate and really

nail down specifically, because as soon as you get specific

about that question, you start to diminish

the value of the study itself.

So the long and short of this is get out into nature

as often as you safely can.

If you can exercise out of doors, even better.

If you want to make it social, great.

If you don't want to make it social, fine.

It's your life.

It's up to you.

But there certainly is value in getting out into nature.

It's also just beautiful from a visual perspective,

from an auditory perspective.

And I myself try and take at least a few trips each year.

None of these are particularly expensive trips

where I try and get out hiking, camping.

The weekly walks in nature are an absolute must for me.

If I miss one because of weather conditions or travel,

I make it a point to try and get into nature

more during the following week or whenever I can.

And frankly, I don't have a scientific explanation

for why nature is oh-so beneficial,

except for the sunlight piece and perhaps this grounding

piece and the negative ionization piece.

And frankly, I don't worry so much

about the lack of variable-isolating, quality,

peer-reviewed studies that support the benefits of getting

out into nature.

I simply like getting out into nature

and into different natural environments

as much as I possibly can, because, for whatever reason,

imagine those reasons have something to do with serotonin,

dopamine, hormones, oxytocin, probably

a bunch of different things that are

rooted in how our nervous system evolved

in natural environments.

Well, it just feels really good.

Thank you for joining for the beginning

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