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A hypnogram is a form of polysomnography; it is a graph that represents the stages of sleep as a function of time. It was developed as an easy way to present the recordings of the brain wave activity from an electroencephalogram (EEG) during a period of sleep. It allows the different stages of sleep: rapid eye movement sleep (REM) and non-rapid eye movement sleep (NREM) to be identified during the sleep cycle. NREM sleep can be further classified into NREM stage 1, 2 and 3. The previously considered 4th stage of NREM sleep has been included within stage 3; this stage is also called slow wave sleep (SWS) and is the deepest stage of sleep.〔 〕 Each of the three NREM stages as well as the period of REM sleep and the awake state can be determined and displayed on a hypnogram. ==Method== Hypnograms are usually obtained by visually scoring the recordings from electroencephalogram (EEGs), electrooculography (EOGs) and electromyography (EMGs).〔 〕 The output from these three sources is recorded simultaneously on a graph by a monitor or computer as a hypnogram. Certain frequencies displayed by EEGs, EOGs and EMGs are characteristic and determine what stage of sleep or wake the subject is in. There is a protocol defined by the American Academy of Sleep Medicine (AASM) for sleep scoring, whereby the sleep or wake state is recorded in 30-second epochs.〔 〕 Prior to this the Rechtschaffen and Kales (RK) rules were used to classify sleep stages.〔 〕 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「Hypnogram」の詳細全文を読む スポンサード リンク
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