Cycles/Stages of Sleep

Most of us have heard of REM (Rapid Eye Movement) sleep. This is a stage of sleep when we dream. Many of us don't remember our dreams when we wake but we all dream. If someone wakes you while you're in the REM stage of sleep, you would probably remember what you were just dreaming about. A person who happens to be watching you while you're asleep will know you're in REM sleep by the movement of your eyes beneath your eyelids.