Dr. Michael Grandner

A lot of people also call it deep sleep.

It's not called deep because it's the good one or the most restful one even.

It's called deep because your arousal threshold is the highest and it is hardest to wake you up from that sleep stage because the thinking parts of your brain are largely like detached and offline.

You're not thinking during that time.

Your muscles are very relaxed.

For athletes, this is super important because this is when growth hormone is secreted in N3 sleep, in stage three or non-REM stage three sleep.

Um, but it's also highly protected.

Even sleep deprived people are mostly getting all of the stage three sleep their body wants.

Like it's, it's actually, again, evolution figured this out a long time ago.

You, it's the hardest to wake up from and it front load, it front loads it into the night.

So usually within the first few hours you're done with it anyway.

So it's not a, so sleep deprivation doesn't actually eat into slow wave sleeper or deep sleep very much.

And people, so they don't need to worry about it so much.

So anyway, you get into that and then you come out of that into an episode of REM.

Um, REM sleep, a lot of people have heard of now, um, is weird.

REM sleep is just fundamentally weird.

So like, this is where dreams and nightmares happen.

Peak blood flow in the brain is actually REM sleep.

Like your brain is extremely active.

It's actually more like waking than many, any other sleep stage.