Why do we move about in our sleep?

Why do we move about in our sleep?

Chris Idzikowski (Director of the Edinburgh Sleep Centre) gives expert video advice on: What happens to my brain when I sleep?; What happens to my muscles when i sleep?; What happens to my breathing when I sleep? and more...

It's a hard question to answer because there's an element of how big of a movement should there be before you classify it as a movement. There's certainly been a lot of work done on moving but we've no real idea, the main thing is probably a lack of comfort.