McKinnon Leela, Shattuck Eric C, Samson David R
Department of Anthropology, University of Toronto Mississauga, Mississauga, ON, CanadaL5L 1C6.
Institute for Health Disparities Research, University of Texas at San Antonio, San Antonio, TX 78249, USA.
Evol Med Public Health. 2022 Nov 22;11(1):53-66. doi: 10.1093/emph/eoac039. eCollection 2023.
Sleep is a vulnerable state in which individuals are more susceptible to threat, which may have led to evolved mechanisms for increasing safety. The sentinel hypothesis proposes that brief awakenings during sleep may be a strategy for detecting and responding to environmental threats. Observations of sleep segmentation and group sentinelization in hunter-gatherer and small-scale communities support this hypothesis, but to date it has not been tested in comparisons with industrial populations characterized by more secure sleep environments.
Here, we compare wake after sleep onset (WASO), a quantitative measure of nighttime awakenings, between two nonindustrial and two industrial populations: Hadza hunter-gatherers ( = 33), Malagasy small-scale agriculturalists ( = 38), and Hispanic ( = 1,531) and non-Hispanic White (NHW) ( = 347) Americans. We compared nighttime awakenings between these groups using actigraphically-measured sleep data. We fit linear models to assess whether WASO varies across groups, controlling for sex and age.
We found that WASO varies significantly by group membership and is highest in Hadza (2.44 h) and Malagasy (1.93 h) and lowest in non-Hispanic Whites (0.69 h). Hispanics demonstrate intermediate WASO (0.86 h), which is significantly more than NHW participants. After performing supplementary analysis within the Hispanic sample, we found that WASO is significantly and positively associated with increased perception of neighborhood violence.
Consistent with principles central to evolutionary medicine, we propose that evolved mechanisms to increase vigilance during sleep may now be mismatched with relatively safer environments, and in part responsible for driving poor sleep health.
睡眠是一种易受伤害的状态，在此状态下个体更容易受到威胁，这可能促使了增强安全性的进化机制的形成。哨兵假说提出，睡眠期间的短暂觉醒可能是一种检测和应对环境威胁的策略。对狩猎采集者和小规模社区的睡眠分段及群体哨兵化的观察支持了这一假说，但迄今为止，尚未在与具有更安全睡眠环境的工业人群的比较中对其进行检验。
在此，我们比较了两个非工业人群和两个工业人群入睡后觉醒时间（WASO，夜间觉醒的定量指标）：哈扎狩猎采集者（n = 33）、马达加斯加小规模农业从业者（n = 38），以及西班牙裔美国人（n = 1531）和非西班牙裔白人（NHW，n = 347）。我们使用通过活动记录仪测量的睡眠数据比较了这些群体之间的夜间觉醒情况。我们拟合线性模型以评估WASO是否因群体而异，并对性别和年龄进行了控制。
我们发现，WASO因群体成员身份而有显著差异，在哈扎人群（2.44小时）和马达加斯加人群（1.93小时）中最高，在非西班牙裔白人中最低（0.69小时）。西班牙裔人群的WASO处于中间水平（0.86小时），显著高于非西班牙裔白人参与者。在对西班牙裔样本进行补充分析后，我们发现WASO与对邻里暴力感知的增加显著正相关。
与进化医学的核心原则一致，我们提出，睡眠期间提高警觉性的进化机制现在可能与相对更安全的环境不匹配，并且在一定程度上导致了睡眠健康不佳。
