Dr. Matt Walker

It's well worth it.

But we're getting very, very close, I would say.

Great.

What about...

I love this topic because there are

hi-fi, lo-fi, and no-fi technologies that you can use.

The story of sleep and temperature, as you mentioned before and reiterated, in terms of the three-part stanza, that tercet that I would describe is, again, you need to warm up to cool down to fall asleep.

You need to stay cool to stay asleep.

You need to warm up to wake up.

What that refers to technically in sleep science are what we call the thermal trigger zones.

So warming up to cool down to fall asleep is what we call the sleep onset thermal trigger zone.

Cooling down or staying cool to stay asleep is about the deep sleep trigger zone.

And then warming up to wake up is the activating alertness trigger zone.

Studies, if you looked at them to begin with before they manipulated that, found something fascinating.

If I take you, Andrew Huberman, and I bring you into my lab and I remove your phone or your laptop and you say goodbye to your friends and family and I bring you into the center and there are no cues as to what time of day, no windows, no nothing.

And I'm just going to say, look, I'll keep asking you, but

at the moment that you feel most sleepy, just let me know.

It turns out that before that, we'd done the delightful intervention of inserting a rectal probe into you, because that's the best way that we can measure your core body temperature.

So we're measuring your core body temperature.

And sure enough, despite you knowing nothing about what time it is,