Dr Sutapa Mukherjee

And I say, oh, I must have been in slow wave sleep.

But then if they ring again, maybe half an hour later, I'll usually answer straight away.

Because if you're in slow wave sleep, your brain is, the way your waves have actually slowed down to such an extent that you really have withdrawn from the world and you may not hear a noise anymore.

It's kind of your body is really wanting to go to sleep.

So are you talking about a nap during the day?

So you're probably, my impression might be that you're really tired and exhausted when you actually get into bed and the fact that you've just gone off to sleep, that your body's ready to start going into the different stages of sleep and then someone wakes you up and that's...

You're just not ready for that.

Your body really needed the sleep for the restorative power of sleep and that's why you wake up and you're really not in a great mood or anything because your body really needs that sleep.

Your body is saying, well, you have to go to sleep right now.

Yes.

I mean, as you've said, it is a form of torture.

So you're not allowed to even through the Geneva Convention, you're not actually allowed to deprive people of sleep.

But some of the studies that have been done, which are really not being done anymore, but have been done on animals where they deprived...

rats of sleep.

And in fact, they deprived them for about 30 days.

And around about that 30 day mark, the rats died and they actually died of sepsis or infection.

So that really shows you the importance of sleep for the immune system.

Well, any infection.

I mean, you know, it's kind of telling you what I said before, that sleep is actually really important for the immune function of our bodies.

You know, any time that you're sleep deprived, you're more at risk of picking up a virus or some other bug infection.