Sleep is considered one of the great mysteries of life. The idea of getting good restful sleep conjures up feeling of peach and comfort, while insomnia can conjure up feelings of dread. Sleep has a distinct architecture with five key stages. Stages 1 and 2 are fairly light, while stages 3 and 4 (or delta wave) sleep are the deeper stages of sleep, followed by REM sleep. Stages 1 and 2 are the non-restful sleep, the type of sleep where you toss and turn or wake up continuously during the night. With only this type of sleep, you will wake up tired and feel a lack of energy during the day. Stages 3 and 4 (delta wave) sleep are the deeper stages of sleep. These are the recuperative stages, the sleep that produces growth hormone, which results in the repair and healing of your body. Stage 5 is REM sleep. This is usually when you will dream. REM sleep will usually occur three to five times each night, each episode increasing in length as the night wears on. .
Sleep is necessary or us to maintain our health in a variety of areas:
Memory and learning
Mood enhancement and social behavior
Growth and development