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

Welcome to the Huberman Lab Podcast, where we discuss science and science-based tools

for everyday life.

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, aka 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 their circadian rhythm.

This is something that I've talked about extensively on the Hubertman 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 hubertmanlab.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 across 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.

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.

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.

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, etc., 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 effective disorder, which is a very bright light that you can look at in

the morning for usually about five to ten 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 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.

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?

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, etc.

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

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 with a hypothesis

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 the

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, right, 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, right?

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 pine cone in its mouth.

It had been chewed down to the cob and the squirrel is probably only about seven or eight

inches long and the pine cone was probably about nine or 10 inches long.

The cob of the, of the pine cone that is.

The interesting thing is that the squirrel was carrying it long ways from the tip of the

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 looks so dedicated and it's 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 contrasts 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 pure 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 desert, 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, which people placed

themselves into forests 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, well, 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 and 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 two 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 two

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 tried 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 to get out

of doors at least a few minutes each day for a morning stroll looking at sunlight, etc. 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 know, 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 a, you know, 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

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Machine-generated transcript that may contain inaccuracies.