Dr Sutapa Mukherjee

But REM sleep is really quite an active part of sleep as opposed to non-REM sleep, a completely different state.

I'm not sure that we could really say that.

I think it's a nice way to think about it, but I don't know that we know for sure why REM sleep is so different.

We do know that in terms of the function of REM sleep, that...

REM sleep is really important for memory consolidation, for emotional processing, and also for brain development.

So, you know, that's why, for example, if we're deprived of REM sleep for whatever reason, and the classic example where that happens is when, say, there's a new baby in the house who's waking up every hour.

So poor mum or dad are

sleep deprived.

But one of the things that really happens is they don't go into REM sleep because you need that other hour of one or two or slow wave sleep before you can get in your first cycle of REM sleep.

That's right.

You have to go through these other stages of sleep.

And so if you're constantly getting woken up every half an hour or an hour, it's really hard to get into REM sleep.

And if you think about how you feel if you're being woken up all night, you really are very irritable and you really don't remember things very well either.

And it's really, really hard to push on during the day if you're just not getting...

that long period to get yourself into REM sleep.

I think all of it is really important, but there have been studies where they've particularly looked at people who are not able to get into REM sleep, and it definitely affects...

Memory and emotional processing, that whole idea of feeling balanced and ready to deal with all the issues that happen during the day very much does require REM sleep.

But even slow wave sleep is really important for REM sleep.

restoring the brain, helping the brain to recover, and also maintaining and consolidating sleep.

So I don't think we can say that one part of sleep is more important.