Dr. Matt Walker

And then we had them go through a full night of sleep, or we then sleep deprived them.

And the next day we were measuring their anxiety.

And in those people who are sleep deprived, we were actually measuring the level of anxiety every hour.

So we could almost get this time lapse photography of what happened to their anxiety state as it unfolded across the sleep deprivation period.

It wasn't a linear response.

that the more and more hours that you were awake beyond 16, the more exponential that rise in anxiety became.

So it wasn't simply a linear dose response curve.

It was exponential, meaning that there was this hockey-shaped swing up.

And in fact, by the next morning, compared to when you'd had a full night of sleep, the

Those individuals were so anxious that almost 50% of the participants in that group who had no signs of anxiety before had a level of anxiety that was so strong that they would reach the diagnostic threshold for having an anxiety disorder.

And that was simply by way of the absence of sleep.

But again, that brought me back to this notion of this is a good experimental tool for us scientists to understand what is the benefit of sleep when it's present and the absence of sleep when it's not by taking sleep completely out of the equation by way of total deprivation.

But of course, that's not real life.

So we did a slightly different study.

Here, what we did was we tracked individuals essentially in the wild, as it were, just going about their daily lives.

And we had different sleep tracking monitoring equipment on them.

So we were tracking their sleep from one night to the next, to the next, to the next.

And from one day to the next, to the next, we were tracking their level of anxiety.

And what we found here was that even small perturbations in their sleep from one night to the next to the next accurately predicted that increase or decrease in their anxiety from one day to the next to the next.

What was the critical ingredient here?