Stages of Sleep Cycle

Stage 2: NREM

Stage lasts 10 to 20 minutes period of sound sleep relaxation progresses body functions continue to slow arousal remains relatively easy

Stage 3: NREM

Stage lasts 15 to 30 min involves initial stages of deep sleep muscles are completely relaxed VS's decline but remain regular sleeper is difficult to arouse and rarely moves

Stage 1: NREM

Stage lasts a few minutes lightest level of sleep Decreased physiological activity begins with gradual fall in VS and metabolism Sensory stimuli such as noise easily arouses person Awakened, person feels as though daydreaming has occured

Stage 4: NREM

Stage lasts approximately 15 to 30 minutes deepest stage of sleep if sleep loss has occurred, sleeper spends considerable portion of night in this stage VS's are significantly lower than during waking hours sleepwalking and bedwetting sometimes occur very difficult to arouse sleeper

REM Sleep

Stages usually begins about 90 mins after sleep has begun duration increases with each sleep cycle and averages 20 minutes vivid, full-color dreaming occurs; less vivid dreaming occurs in other stages. Stage is typified by rapidly moving eyes, fluctuating heart and respiratory rates, increased or fluctuating blood pressure, loss of skeletal muscle tone, and increase of gastric secretions. very difficult to arouse sleeper