e sleep (Gottlieb 80). REM sleep occurs mostly in the morning hours and is when dreaming occur. The other type of sleep is called NREM (non-rapid eye movement) sleep, which leaves a sense of refreshment to the body. NREM sleep is also called quiet sleep (Gottlieb 81). Stages of sleep alternate between REM and NREM states that are characterized by brain waves, muscle activity, eye movements, heart function, and breathing (Cohen 8). These characteristics can be measured using observation, and sophisticated instruments such as an encephalograph (Mosby NP). The encephalograph measures brain waves and record them for analysis. This is how stages are distinguished (Cohen 8). NREM has four stages in it that range from stage I, which is drowsiness, to stage IV, which is deep sleep (Gottlieb 81). Stage I is a short period that lasts about five minutes and is the transitional period from being drowsy to being asleep. Stage II is often called light sleep and lasts between ten to forty-five minutes (Cohen 8). Stage III begins the first instance of deep sleep; where the brain, heart, lungs, and muscles relax and slow down. Stage IV is described as the deepest sleep, and together with stage III lasts up to sixty minutes (Cohen 9). NREM occurrences include night terrors, sleeptalking, and sleepwalking (Gottlieb 81), which occur when a body wakes incompletely while they are not dreaming (Cohen 155). Researchers believe that memories are stored in long-term memory during REM sleep. This is due to the activity of nerve cells during REM sleep, which is active sleep (Cohen 9). This understanding of sleep goes beyond the concepts of rest. By digging deeper, researchers have found many logical aspects of sleep that give us insight into understanding. With this understanding, we can see the aspects of health that stem from a r
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