Why do children often wake in their sleep?

Why do children often wake in their sleep?

Chris Idzikowski (Director of the Edinburgh Sleep Centre) gives expert video advice on: Why do some people need more sleep than others?; Do children or adults need more sleep?; Do elderly people need more sleep? and more...

Certainly their cycle of awakening is shorter then an adult's. So the odds of an adult being awoken out of their sleep are high if children are running at 50 minutes and the adults are running at 90 minutes. But there is no strong reason why there should be a large number of awakenings other than discomfort or ailments or whatever.