Dr. Matt Walker

So maybe I can firstly address what is...

what is sleep doing and what happens if we're not getting sufficient sleep?

And then the other question is, what is good sleep?

In terms of what sleep is doing and why he was right in saying that mother nature didn't make a blunder.

And it hasn't, by the way, because if you go back, every species that we have carefully studied to date seems to sleep.

And what that tells us, even, you know, very old, evolutionary old, ancient earthworms seem to sleep.

They will have a period of what we call the Thargicus, which is where they'd seem to be inactive.

So I bring that point up because it means that sleep appears to have evolved with life itself on this planet, and then it has fought its way through heroically every step along the evolutionary path.

And that by itself must tell us that whatever sleep is doing, it must be non-negotiably life support necessary.

in what ways is it life support necessary well we now know many of those first when you're not getting sufficient sleep i can speak about your hormonal systems let's say i take a group of really healthy young men and i limit them to four or five hours of sleep for five nights

they will have a level of testosterone, which is similar to someone who is probably 10 years older than them.

So a lack of sleep will age you within five days by a decade.

We also see equivalent impairments in female reproductive health caused by lack of sleep, impairments in estrogen, in follicle stimulating hormone, and also in luteinizing hormone.

There is some degree of a dose response curve, but we haven't mapped it out with high... So the way I would want to do it as a sleep scientist would say, okay, I'm going to do this for one night and I'm going to thin slice you to seven hours, six hours, five hours.

And then I'm going to do it for two nights.

And you're going to, again, be in the six hours, seven hours, four hours.

And I would like to build up this high fidelity map and understand that we don't have that.

But certainly what we know is that a night of total deprivation will...

markedly impair those hormones.

And we know that after about a working week of short sleep, you see those impairments too.