Shining Evolutionary Light on Human Sleep and Health
Scientists have made substantial progress in understanding the evolution of sleep across the Tree of Life, including in primates. Remarkably, evolutionary changes in sleep along the human lineage have been largely ignored. This omission is surprising given the extraordinary mental capacity and behavioral flexibility of humans, and the importance of sleep for cognitive performance. Based on new evolutionary analyses and studies of sleep in traditional human populations, I propose that human sleep is highly derived relative to other primates. Specifically, humans are more flexible in their sleep patterns than other great apes, and human sleep is shorter and exhibits a higher proportion of REM than expected, compared to other primates. While many sleep scientists lament the continued erosion of sleep in modern life, our new findings suggest that natural selection has been hard at work for millions of years to shorten human sleep. I will identify selective pressures that may play a role in favoring shorter sleep in humans, and I will consider the consequences of these evolutionary changes for understanding human sleep disorders, health across the lifespan, and health disparities.