Dr. Matt Walker

For most people, even if you're a morning type or evening type, by about 11 a.m., by about 11 a.m.

midday, you're really starting to get to your peak.

Most people are somewhere either side of the peak or around that peak.

I would say that if you are feeling groggy and not alert and awake at 11, 11.30, depending on your chronotype,

I would use that as probably the better metric of my daytime sleepiness.

And by the way, it's very interesting that that peak, if you look at that circadian peak, when you're at your optimal, it's both your optimal for your brain, but it's also for your body.

It's the point at which your core body temperature starts to peak.

That's the moment where you have optimal physiology.

And when you look at world records that have been broken in the Olympics and you plot them on the basis of time of day, you see this incredible beautiful spike where most people are breaking world records right in that circadian sweet spot around that midday period.

Why?

It's because that's the period where human physiology seems to be at its optimal thermal

temperature at least.

Fascinating, fascinating.

But on average, that's the way you'll see it.

Yeah.

Yeah.

And that fits both with your brain.

And my guess is that if we were to get you into the gym and have you go through your routine and see if we could do that routine once we've got a basal metric, set of metrics, I will have you do it at 7 a.m., then have you do it at 9 a.m., then do it at midday, then 3 p.m., then 6 p.m., and then 10 p.m.

same workout, same human being, but there will be definitive periods of time in the day when you are optimal.

And my guess is that that optimality of brain is matched by optimality of body such that your peak performance output and let's say your peak jump height or your peak muscle strength would be right around those time periods that fit with your own circadian chronotype rhythmicity.