Dr. Matt Walker

In other words, you can't get pleasure from normally pleasurable things.

It's not an issue about sliding down to the negative.

It's the absence of being able to experience the positive that puts you on a track towards depression.

And what you and I discussed earlier in this episode is some of the work that we've been doing, where when you sleep deprive individuals, but you show them very rewarding based stimuli, they become much more reward sensitive.

And perhaps this is why patients will respond to sleep deprivation with depression, because they're too far away from that positive end of the spectrum.

They're not reward sensitive enough.

They don't get a positive good feeling.

Now, if you're someone who is healthy and you're sleep deprived, you go too far in the reward direction and you become vulnerable to reward and sensation seeking.

But if you're depressed and you're shifted to sort of away from that and sleep deprivation brings you back closer to a normative reward-based reactivity, maybe that's the reason why you get this antidepressant benefit and why when you start sleeping again,

you take away that enhanced reward sensitivity and you lose the antidepressant benefit.

So I think we still don't know enough about depression and sleep yet.

If you were to ask me of the four, quantity, quality, regularity, and timing, which would be ideal?

I would say all four are definitely players, but timing may have some of the best evidence because it's not just about sleep when it comes to depression.

It's also about your circadian rhythm, that if you are not aligned with your natural chronotype, your natural 24-hour rhythm, circadian misalignment when you fall out of synchrony with your natural chronotype,

is a strong predictor of depression.

So if there is an actionable item, first, it would be to say from a big picture perspective, understand that sleep is one of the

available options for you as a no cost to try to stabilize your mental health.

Now, I'm not suggesting that all psychiatric conditions are sleep disorders.

That's not true.

And I'm not suggesting that you should stop