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Middle-of-the-night insomnia (MOTN) is characterized by having difficulty returning to sleep after waking up during the night or very early in the morning. It is also called nocturnal awakenings, middle of the night awakenings, sleep maintenance insomnia, and middle insomnia. This kind of insomnia (sleeplessness) is different from initial or sleep-onset insomnia, which consists of having difficulty falling asleep at the beginning of sleep. The disrupted sleep patterns caused by middle-of-the-night insomnia make many sufferers of the condition complain of fatigue the following day. Excessive daytime sleepiness is reported nearly two times higher by individuals with nocturnal awakenings than by people who sleep through the night. However, sleep research conducted already in the 1990s showed that such waking up during the night is in fact a natural sleep pattern that is actually beneficial, rather than a form of insomnia. If interrupted sleep (called "biphasic sleeping" or "bimodal sleep") is perceived as normal and not referred to as "insomnia", less distress is caused and a return to sleep usually occurs after about one hour.〔http://www.bbc.com/news/magazine-16964783〕 ==Prevalence== Waking up in the middle of the night, or nocturnal awakening, is the most frequently reported insomnia symptom, with approximately 35% of Americans over 18 reporting waking up three or more times per week.〔 Of those who experience nocturnal awakenings, 43% report difficulty in resuming sleep after waking, while over 90% report the condition persisting for more than six months. Greater than 50% contend with MOTN conditions for more than five years. A 2008 "Sleep in America" poll conducted by the National Sleep Foundation found that 42% of respondents awakened during the night at least a few nights a week, and 29% said they woke up too early and couldn’t get back to sleep. Other clinical studies have reported between 25% and 35% of people experience nocturnal awakenings at least three nights a week. 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「Middle-of-the-night insomnia」の詳細全文を読む スポンサード リンク
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