Sophie Bostock

We tend to increase our perception of threat when we're sleep deprived.

And I think this is an incredibly important theme that will probably sort of run through this conversation because that sense of threat, that is not just psychological.

That is very much physiological.

So if your brain and your body are feeling on edge, then what happens?

You amp up that sensitivity of the stress response, this physiological cascade which has evolved to help us to fight or flee or freeze in the face of danger.

And for most of us, that means increasing adrenaline, increasing cortisol, increasing blood pressure, increasing the blood flow to the muscles, perhaps making us

sweat a little bit more, mobilizing blood sugar, blood glucose, so that we're fired up for action.

So that is an evolutionary response to being in an environment where we couldn't sleep well.

So if you think about our hunter-gatherer ancestors, you know, if they were camped out next to a den of saber-toothed tigers, there was an evolutionary advantage in being in this increased state of fight or flight.

They were much less likely to get eaten.

And over hundreds of thousands of years, our brains have learned to associate sleep loss with potential danger.

And so we are more on edge.

So that helps to explain those emotional responses, also the physiological responses that over time our immune system becomes dysregulated, more like to be exhausted almost, because we're constantly ramping up our immune response ready to fight infection.

We also see that we're at increased risk of hypertension, of inflammation, these diseases which help to increase risks of heart disease, of diabetes, disrupted blood sugar.

I could go on.

But I think the other aspect is cognitive function.

So we know that the brain does a huge amount of mental processing overnight.

We are consolidating memories.

We are pruning back information so that we can focus on what is most important.

So sleep is really helping us to learn and innovate.