The human sleep pattern is paradoxical. Sleep is vital for optimal physical and cognitive performance, yet humans sleep the least of all primates. In addition, consolidated and continuous monophasic sleep is evidently advantageous, yet emerging comparative data sets from small-scale societies show that the phasing of the human pattern of sleep–wake activity is highly variable and characterized by significant nighttime activity. To reconcile these phenomena, the social sleep hypothesis proposes that extant traits of human sleep emerged because of social and technological niche construction. Specifically, sleep sites function as a type of social shelter by way of an extended structure of social groups that increases fitness. Short, high-quality, and flexibly timed sleep likely originated as a response to predation risks while sleeping terrestrially. This practice may have been a necessary preadaptation for migration out of Africa and for survival in ecological niches that penetrate latitudes with the greatest seasonal variation in light and temperature on the planet.

中文翻译：

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人类睡眠悖论：智人意想不到的睡眠习惯

人类的睡眠模式是自相矛盾的。睡眠对于最佳的身体和认知表现至关重要，但在所有灵长类动物中，人类睡眠最少。此外，巩固和连续的单相睡眠显然是有利的，但来自小规模社会的新兴比较数据集表明，人类睡眠-觉醒活动模式的分阶段是高度可变的，并且以显着的夜间活动为特征。为了调和这些现象，社会睡眠假说提出，人类睡眠的现存特征是由于社会和技术生态位的构建而出现的。具体来说，睡眠场所通过增加健康的社会群体的扩展结构，起到一种社会庇护所的作用。短暂、高质量和灵活定时的睡眠可能起源于在陆地上睡觉时对捕食风险的反应。