Dr. Matt Walker

What was the critical ingredient here?

Well, in the first experiment, I'd essentially manipulated both quantity and quality, the two QQs of the QQRT.

I'd removed the quantity of sleep, and also they had no quality of sleep.

Why?

Because they had no quantity of sleep.

But when we looked at that day-to-day-to-day, night-to-night-to-night study, it wasn't quantity that was the best predictor.

It wasn't shortening of quantity that determined next day increases in anxiety.

It was quality.

The worse the quality was night-to-night-to-night, the worse their anxiety became.

So that started to lead us to think a lot more about what is it regarding the quality of sleep that seemed to offer when it was present, what I would describe as an anxiolytic benefit.

In other words, it's lessening anxiety.

A lack of sleep is an anxiogenic.

It's going to produce anxiety.

What in sleep is anxiolytic?

We started off with a hypothesis that was profoundly incorrect.

We thought, well, for emotions, which are these short bursts of affective state, it was REM sleep that seemed to be the principal ingredient.

Well, wouldn't that be the case for mood states?

Well, here with anxiety, it wasn't.

It was deep non-REM sleep and we couldn't get away from it.

And so what we found was that when we looked at the sleep in the laboratory and asked, what was predictive from the night before?