Dr. Matt Walker

I'm just going to stay here and lie in bed.

I'm awake.

I'm not asleep.

And so we don't quite know yet if depression is a condition that is associated with long sleep.

We certainly know it's associated with short sleep and disrupted sleep or that is masquerading as this thing called hypersomnia.

But when you really look at the data, it's not quite so clear.

That was the first peculiarity in depression that there could be this paradox of yes, long sleep, but also not enough sleep, too short sleep.

One of the earliest findings in depression and sleep and has been quite well replicated is a change in REM sleep.

But now it wasn't necessarily that individuals who had depression slept or had excessive amounts of REM sleep.

They had a little bit more.

What was interesting is that when that REM sleep emerged during the night was much earlier.

And in the first episode, I was telling you that when your head hits the pillow, you go down to the light stages of non-REM, then into the deeper stages, and then maybe after about 50, 60, 70, 80 minutes, you'll pop up and you'll have your short REM sleep period.

But that first REM sleep period in people with depression seemed to have been called up by the brain, abnormally or not, much earlier.

So it's what we call REM sleep latency.

You can say, well, perhaps that's because Matt, you also spoke to me that REM sleep may be important for some aspects of the emotional brain.

And when you are depressed, the brain knows that REM sleep is required and it calls it up on the menu of the series of dishes that you're going to be served earlier on in the night because it's needed more significantly.

The other, and that's the adaptive theory, the other is the maladaptive theory, which is that arriving...

with your REM sleep too early does not do your brain good things.

And therefore it's some abnormality of emotional processing.

The data that's interesting there is that if you look at some antidepressants, many of them will either delay the onset of REM sleep or they will reduce it significantly.