Welcome to Huberman Lab Essentials, where we revisit past episodes for the most potent and actionable science-based tools for mental health, physical health, and performance.

I'm Andrew Huberman, and I'm a professor of neurobiology and ophthalmology at Stanford School of Medicine.

Today I have the pleasure of introducing Dr. Craig Heller as my guest on the Huberman

Lab podcast. And now for my discussion with Dr. Craig Heller. Great to have you here. It's good to be here.

Yeah. I know that I and many people have a lot of questions about the use of cold. So one of the things

that's happened in recent years is that for many reasons, people have

become interested in things like taking cold showers and taking ice baths for many different

purposes. Could you just tell me a little bit about what happens when I get into a cold shower or an ice bath?

Well, first of all, you get a tremendous shock.

And what that's going to translate into is a bit of a shot of adrenaline.

And I think this is really the so-called benefit, but it doesn't necessarily translate into any benefit in terms of your

physiology or performance and so forth. Now, if you take a cold bath or a cold shower,

a couple of things are happening. One is you're going to stimulate vasoconstriction. So if anything,

it's going to make it a little bit more difficult for your body to get rid of heat because you're going to stimulate vasoconstriction. So if anything, it's going to make it a little bit more difficult for your body to get

rid of heat because you're shutting off your avenues of heat loss.

If you're in a true cold bath, the overall surface area of your body is so great that it doesn't matter if you've as constricted,

you're still going to lose heat. The primary sites of heat loss, which we're going to get into,

are the palms of your hands, the soles of your feet, and the upper part of your face. And the reason

these are avenues for heat loss is they're underlain by special blood vessels.

And these blood vessels are able to shunt the blood from the arteries, which coming from the heart, directly to the veins, which are returning to the heart, and bypassing the capillaries, which are the nutritive vessels, but high resistance.

So you can tell when you shake someone's hand what his or her thermal status is.

The hand's hot or it's cold.

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