What are the Stages of Sleep?

There are four stages of sleep. The first stage is light sleep where you drift in and out of sleep. Stage 2 eye movement stops and brain waves become slower. Stage 3 delta waves are interspersed with faster waves. Stage 4 is referred to as deep sleep. In this stage it is very difficult to wake someone. Then you will have the REM period of sleep. Most people experience three to five intervals of REM sleep each night.