What causes sleepwalking?

I have heard about sleepwalking, but I do not really know much about it. I will tell you some of the things I have read about it.

First, you should know that all of us move around a little even when we think we are fast asleep. Almost everyone has eye movements and many people show lip movements. Everyone has dreams. So I suppose that sleepwalking might be like acting out a dream.

Sleepwalking has a special fancy name: somnambulism. But the fact that we have a fancy word for it does not mean that we understand it. I have read that some people think that sleepwalkers are just absent-minded dreamers. So far as I can tell, there is no danger in waking up someone who is sleepwalking.