We know enough about what sleep is though we don't know what exactly causes sleep. Sleep is a state of rest - an unconscious rest. when we sleep, our body recovers from fatigue caused by the day's activities. After a good sleep and the rest that it gives, we become alert and active again ready for the normal activities of the day. When we wake up in the morning, it is not always possible for us to remember what happened when we were asleep. We may remember a dream but the rest of our sleep was a kind of darkness in which nothing seems to have taken place. Several things happen to out body while we are sleeping. As we sink deeper into sleep, muscles relax more and more. Our heartbeat becomes slower. Our temperature and blood pressure go down. the ever active brain also slows down so that we can't think or act consciously. But we dream. When we wake up our temperature and blood pressure rise to normal. Our heartbeat and breathing also become normal and we are fully awake and have forgotten most if not all the dreams that we had while sleeping. What is a dream? It is an activity of the mind that takes place when we are asleep. Some drems are probable while others are not. That only means that money of the things that happen in dreams could happen when we we awake. Others could