Dr. Matt Walker

under conditions of sleep deprivation.

That is quite a striking amplification.

In fact, we, to that date, with all of our studies on sleep and sleep loss, had not quite seen an effect size within the brain that was that big.

So the way we did the analysis first was we used almost a correlation approach.

So we sort of told the brain imaging analysis to say, look, here are the ratings of these pictures.

And they go from very neutral to increasingly negative and aversive.

And show me what in the brain is reacting to that curve, that gradient curve.

And sure enough, you've got the magnitude overall was 60%.

But it's a very interesting point that you make because where the amygdala started to respond and that responsivity started to hook up in the activation and the sort of aggravation direction was much earlier in the curve of emotionality.

In other words, things that previously when you've had a good night of sleep were

do not feel particularly emotional, started to become rather emotional when you were not getting sufficient sleep.

So it heightened the sensitivity of the initial triggering of the emotional response.

And then the more emotional it became, the more separate those two sort of reactivity curves became from the amygdala when you had sleep versus when you had not sleep or had not slept, I should say.

To us then the question became, well, why?

Why is the amygdala so reactive and uncontrolled when you are absent sleep?

And we did another analysis.

And what we found was that there was a structure in your frontal lobe.

And the frontal lobe just sits directly.

Sort of if you think about your eyes and you go directly up, you're in your frontal lobe.

And it was a particular part of the frontal lobe, the middle part that sits right between your eyes, something that we call the medial prefrontal cortex.