Dr. Matthew Walker

In other words,

Rats will die almost as quickly from sleep deprivation as they will from food deprivation.

It's that essential.

But then they did something different.

They said, well, what about the different stages of sleep?

So they selectively deprived them of either non-REM sleep and REM sleep.

The hypothesis was perhaps that non-REM sleep is, from an evolutionary perspective, a much older form of sleep.

The first stage of sleep that came into being was non-REM sleep.

And the way we answer that is we look across phylogeny and these sort of different branches.

And what we find is that in insects and in reptiles, amphibians, and fish,

they all seem to have non-REM sleep.

But for the most part, with a few exceptions, they don't seem to have REM sleep.

But if you look at birds and mammals, they do have REM sleep.

And in fact, it seems as though REM sleep evolved twice independently, once in birds, once in mammals, which tells us probably that it's essential if it's being forced through the evolutionary pipe twice independently.

So you would argue, well, if I selectively deprived you of non-REM, the older stage of sleep, presumably that's more life support necessary, and REM sleep, REM sleep is the new kid on the block evolutionarily.

They found the opposite.

They found that if they selectively deprived rats just of non-REM sleep, they did die, but it took them longer.

They died after about 60 days.

If you deprive them of REM sleep, dream sleep, they died after 40 days versus 60 days.

The words, this new type of sleep, REM sleep, seems to be on that basis, maybe even more important to supporting life.