A sleep epidemic or enlightenment? A Bayesian approach to test the sleep epidemic hypothesis shows foragers have short and fragmented sleep compared to large scale societies

Human sleep is linked with nearly every aspect of our health and wellbeing. The question whether and to what extent human sleep is in a state of evolutionary mismatch has gained recent attention from both clinical and biological science researchers. Here, I use a comparative Bayesian approach aimed at testing the sleep epidemic hypothesis - the idea that, due to labor demands and technological disruption, sleep-wake activity is negatively impacted in post-industrial, economically developed societies. In contrast to the expectations of the sleep epidemic hypothesis, when compared to both large and small-scale subsistence societies that rely on agriculture for subsistence, foragers were the shortest, least efficient sleeping group. Coupled with previous work demonstrating that foragers have stronger circadian rhythms compared to those sleeping in buffered environments, I present the sleep-rhythm trade-off hypothesis - that sleep duration, quality, and synchrony is driven by trade-offs between sleep security and comfort versus sleep site environmental exposure. One strategy to improve wellbeing of modern sleepers would be to focus on behavioral interventions that reduce desynchronizations of circadian rhythms, while holding the positive ground of safe, secure, and regulated sleep environments typical of economically developed societies.