Environmental determinants of human sleep timing, duration and continuity: studies in hunter gatherers

摘要 许多健康问题被归咎于“现代”文明带来的变化。 要了解现代环境的变化如何影响健康，需要与 生活在前现代环境中的人类。以传统方式生活的群体数量迅速增加， 逐渐减少电气化和美洲原住民保留地的经济发展消除了这种 几十年前，美国。世界其他地区也在开展类似的工作。只有少数几组 狩猎采集者仍然存在。我们开始了一项关于非工业人类睡眠的研究，以验证人们普遍认为， “现代”人类的睡眠时间比进化后的“自然”时间要少得多。我们发现，令人惊讶的是，在当时 我们研究的三组人的睡眠时间都低于大多数人， 工业社会的研究。此外，我们发现夏季和冬季之间有近1小时的差异， 在两个季节，我们对两组人的睡眠时间进行了为期1周的采样，解决了长期存在的问题。 关于人类睡眠时间是否对季节变化有反应的争论。先前的共识是， 在持续时间上没有差异或仅有微小变化。我们还发现，与其他灵长类动物不同， 在自然环境中，它们通常不会在日落时开始睡觉，也不会在日出时醒来。而是睡觉 日落后数小时发病，日出前30-60分钟醒来。的时间点 经过检查，我们的初步研究表明，狩猎采集者在睡眠时不显示外周血管舒张， 发病但是，他们在觉醒时会外周血管收缩。相反，实验室研究表明，“现代” 人类具有相反的模式，在睡眠开始时外周血管舒张，但在睡眠开始时外周血管舒张， 觉醒后血管收缩。最引人注目的是，狩猎采集者没有报告或表现出大量的 失眠率低于2%，而所有工业社会的失眠率为10-15%。我们的数据 表明环境温度和体温调节对日温度周期反应 在生理调节、功能和病理学中， 人类的睡眠几乎所有关于人类和动物睡眠时间的研究都是在恒定的时间内进行的， 热中性温度，并集中在电灯的作用。我们建议记录睡眠， 核心、外围和环境温度以及自然条件下的环境光照水平， 通过全年连续监测受试者的状况。我们的综合方法将使我们能够 比较光照和温度对睡眠时间、EEG定义的睡眠状态和警觉性的影响。这些将 这是第一次在自然条件下进行这样的研究， 与REM和非REM睡眠有差异的参数，EEG频谱，睡眠持续时间，睡眠连续性和 白天的警觉性这些数据可以解释狩猎采集者几乎没有失眠的原因， 普遍存在于工业化社会，并建议治疗，以扭转这种疾病。

Abstract Many health disorders have been attributed to the changes brought about by “modern” civilization. Understanding how the changes in the modern environment are affecting health requires comparison with humans living in the pre-modern environment. The number of groups living in the traditional way is rapidly diminishing. Electrification and the economic development of Native American reservations eliminated such groups in the US decades ago. A similar process is ongoing in other regions of the world. Only a few groups of hunter-gatherers remain. We began a study of sleep in non-industrial humans to test the widespread belief that “modern” humans sleep much less than the evolved “natural” amount. We found that, surprisingly, at the time points that we sampled, sleep durations in all three groups we studied were lower than those seen in most studies of industrial societies. Furthermore, we found a nearly 1 hour difference between summer and winter sleep durations in the two groups we sampled for 1 week periods in both seasons, settling the longstanding controversy over whether human sleep durations respond to seasonal changes. The prior consensus was that there was no difference or only a minor change in duration. We also found that, unlike other primates, humans in the natural environment do not typically start sleep at sunset nor do they awaken at sunrise. Rather, sleep onset is several hours after sunset and awakening is 30-60 minutes before sunrise. At the time points examined, our preliminary studies suggest that hunter-gatherers do not show peripheral vasodilation at sleep onset. But, they peripherally vasoconstrict upon awakening. In contrast, laboratory studies show that “modern” humans have the opposite pattern, peripherally vasodilating at sleep onset but not peripherally vasoconstricting upon awakening. Most strikingly, hunter-gatherers do not report or exhibit substantial levels of insomnia, with rates under 2%, in comparison to the 10-15% rates reported in all industrial societies. Our data suggest that environmental temperature and the thermoregulatory responses to the daily temperature cycle may be as important, or more important, than light level in the physiological regulation, function and pathology of human sleep. Nearly all studies of the timing of human and animal sleep have been conducted at constant, thermoneutral temperatures and have focused on the role of electric light. We propose to record sleep and core, peripheral and ambient temperature as well as ambient light levels under natural, evolutionarily relevant conditions by monitoring subjects continuously across an entire year. Our integrated approach will allow us to compare the effect of light and temperature on sleep time, EEG defined sleep states and alertness. These will be the first such studies under natural conditions and will provide insights into the temperature and light parameters differentially linked to REM vs nonREM sleep, EEG spectra, sleep duration, sleep continuity and daytime alertness in humans. This data may explain the virtual absence of insomnia in hunter-gatherers, its ubiquity in industrialized societies, and suggest treatments to reverse this disorder.