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Non-rapid eye movement sleep, or NREM, is, collectively, sleep stages 1–3, previously known as stages 1–4. Rapid eye movement sleep (REM) is not included. There are distinct electroencephalographic and other characteristics seen in each stage. Unlike REM sleep, there is usually little or no eye movement during these stages. Dreaming is rare during NREM sleep, and muscles are not paralyzed as in REM sleep. People who do not go through the sleeping stages properly get stuck in NREM sleep, and because muscles are not paralyzed a person may be able to sleepwalk.〔OConnell, C. (2010, Mar 09). Why do some people sleepwalk? ''Irish Times'', pp. 7. Retrieved from http://ezproxy.qa.proquest.com/docview/309237844?accountid=14771.〕 According to studies, the mental activity that takes place during NREM sleep is believed to be thought-like, whereas REM sleep includes hallucinatory and bizarre content.〔Manni,Raffaele. "Rapid Eye Movement Sleep, Non-rapid Eye Movement Sleep, Dreams, and Hallucinations". 2005;7:196-197.〕 The mental activity that occurs in NREM and REM sleep is a result of two different generators, which also explains the difference in mental activity.〔Manni,Raffaele. "Rapid Eye Movement Sleep, Non-rapid Eye Movement Sleep, Dreams, and Hallucinations". 2005;7:196-197.〕 In addition, there is a parasympathetic dominance during NREM. During the period of Non-REM sleep, the mindset of a person is more organized. The differences in the REM and NREM activity reported is believed to arise from differences in the memory stages that happen during the two methods of sleep.〔Manni,Raffaele. "Rapid Eye Movement Sleep, Non-rapid Eye Movement Sleep, Dreams, and Hallucinations". 2005;7:196-197.〕 It has been found through several experiments that low levels of stage 3 sleep are found in about 40-50% of acute and chronic schizophrenics who typically portray abnormal non-rapid eye movement sleep.〔Hiatt John F., Floyd Thomas C., Katz Paul H., Feinberg Irwin. "Further Evidence of Abnormal Non-Rapid-Eye-Movement Sleep in Schizophrenia" (1985). Volume 42. New York: Northport.〕 ==Stages of NREM sleep== NREM sleep was divided into four stages in the Rechtschaffen and Kales (R&K) standardization of 1968. That has been reduced to three in the 2007 update by The American Academy of Sleep Medicine (AASM). * Stage 1 – occurs mostly in the beginning of sleep, with slow eye movement. This state is sometimes referred to as relaxed wakefulness. Alpha waves disappear and the theta wave appears. People aroused from this stage often believe that they have been fully awake. During the transition into stage-1 sleep, it is common to experience hypnic jerks.〔National Institute of Neurological Disorders and Stroke, (Understanding sleep )〕 * Stage 2 – no eye movement occurs, and dreaming is very rare. The sleeper is quite easily awakened. EEG recordings tend to show characteristic "sleep spindles", which are short bursts of high frequency brain activity, and "K-complexes" during this stage. * Stage 3 – previously divided into stages 3 and 4, is deep sleep, slow-wave sleep (SWS). Stage 3 was formerly the transition between stage 2 and stage 4 where delta waves, associated with "deep" sleep, began to occur, while delta waves dominated in stage 4. In 2007, these were combined into just stage 3 for all of deep sleep. Dreaming is more common in this stage than in other stages of NREM sleep though not as common as in REM sleep. The content of SWS dreams tends to be disconnected, less vivid, and less memorable than those that occur during REM sleep. This is also the stage during which parasomnias most commonly occur. Various education systems e.g. the VCAA of Australian Victorian education practice still practice the stages 3 & 4 separation. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Non-rapid eye movement sleep」の詳細全文を読む スポンサード リンク
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