What do we know about sleep?
All animals (including humans) need sleep for their survival and, as we have already said, people's bodies will always try to manage as much sleep as they need. But, although sleep takes up a big chunk of our lives, scientists are still researching why we actually need to sleep. One idea is that while we are asleep our body and brain uses the time to repaire itself. Likewise, there have been many theories as to why we dream and what dreams may mean if they mean anything at all. Again, scientists don't really know but they think it may have something to do with how we organise and remember information we have taken in from the previous day or other earlier experiences that need filing away. Throughout the night we move through different stages of sleep, from light sleep to deep sleep, to dream sleep, and then back to the beginning again. We can go through this cycle several times a night and, as the night progresses, we tend to spend more time in dream sleep. We typically spend about two hours each night drreaming even though we may remember nothing in the morning.
