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

摘要 许多健康障碍都归因于“现代”文明带来的变化。 要了解现代环境的变化是如何影响健康的，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正在迅速增加 在逐渐减少。电气化和美洲原住民保留地的经济发展消除了这种 几十年前在美国的团体。世界其他地区也在进行类似的进程。只有少数几组 狩猎-采集者仍然存在。我们开始了一项对非工业人类睡眠的研究，以检验人们普遍认为 “现代”人类的睡眠比进化后的“自然”睡眠要少得多。我们发现，令人惊讶的是，当时 我们抽样点，我们研究的所有三组的睡眠持续时间都比大多数人看到的要短 对工业社会的研究。此外，我们发现夏季和冬季之间有近1小时的差异 我们在两个季节采样了一周的两组人的睡眠时间，解决了长期存在的 关于人类的睡眠持续时间是否会对季节变化做出反应的争议。之前的共识是 持续时间没有差别，或者只有很小的变化。我们还发现，与其他灵长类动物不同，人类 在自然环境中，通常不会在日落时开始睡觉，也不会在日出时醒来。更确切地说，睡觉 发病时间为日落后数小时，醒来时间为日出前30-60分钟。在这些时间点 经过检查，我们的初步研究表明，狩猎-采集者在睡眠时不会表现出外周血管扩张 开始了。但是，它们在觉醒时会发生外周血管收缩。相比之下，实验室研究表明，“现代” 人类有相反的模式，睡眠开始时外周血管扩张，但不是外周血管扩张 苏醒后血管收缩。最引人注目的是，狩猎-采集者并没有报告或展示出大量的 失眠率低于2%，而所有工业社会报告的失眠率为10%-15%。我们的数据 表明环境温度和体温调节对每日温度循环的反应 在生理调节、功能和病理方面，可能与光水平一样重要，甚至更重要 人类睡眠的一部分。几乎所有关于人类和动物睡眠时间的研究都是恒定进行的， 温度和中温都集中在电灯的作用上。我们建议记录睡眠和 在自然、进化相关的情况下，核心、外围和环境温度以及环境光水平 通过连续监测受试者一整年的情况。我们的综合方法将使我们能够 比较光线和温度对睡眠时间的影响，EEG定义了睡眠状态和警觉性。这些遗嘱 是第一个在自然条件下进行这样的研究，并将提供对温度和光线的洞察 与快速眼动睡眠和非快速眼动睡眠、脑电频谱、睡眠持续时间、睡眠连续性和 人类白天的警觉性。这一数据可能解释了为什么狩猎-采集者实际上没有失眠，它的 在工业化社会中无处不在，并建议扭转这种疾病的治疗方法。

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.