This award was provided as part of NSF's Social, Behavioral and Economic Sciences (SBE) Postdoctoral Research Fellowships (SPRF) program and SBE's Biological Anthropology program. The goal of the SPRF program is to prepare promising, early career doctoral-level scientists for scientific careers in academia, industry or private sector, and government. SPRF awards involve two years of training under the sponsorship of established scientists and encourage Postdoctoral Fellows to perform independent research. NSF seeks to promote the participation of scientists from all segments of the scientific community, including those from underrepresented groups, in its research programs and activities; the postdoctoral period is considered to be an important level of professional development in attaining this goal. Each Postdoctoral Fellow must address important scientific questions that advance their respective disciplinary fields. Under the sponsorship of Dr. Jerome Siegel at the University of California, Los Angeles, this postdoctoral fellowship award supports an early career scientist investigating sleep patterns in a modern hunter-gatherer population. Most people find it impossible to start their day without an alarm clock and a cup of coffee, but San hunter-gatherers do not have such amenities. During human evolution, early humans needed to figure out what time they needed to wake up each day and go to sleep each night in order to maximize their reproductive success in the context of a traditional hunter-gatherer lifestyle. The San population lives a similar lifestyle today, with most plant food being collected from wild sources, and all meat coming from hunting wild animals with bow-and-arrow. They live in a remote village where they do not have access to electricity or running water. People spend almost all of their time outside, including sleeping outside, except for when rain is expected.
Earlier work in this and two other similar populations found that sleep duration is 5.7-7.1 hours per night, similar to the typical sleep duration observed in the United States. Sleep is normally initiated several hours after sunset and terminated at the coldest time of the 24-hour day. People sleep one hour longer per night in the winter months than they do in the summer months. These similarities in sleep patterns across three independent populations may be driven by biological adaptations to the natural environment. The follow-up research in this fellowship investigates how ambient conditions affect sleep within the San population. Changes in sleep timing and duration across the year, measured with wrist-worn accelerometers, can be analyzed in tandem with weather data to assess the relative influence of light and temperature on sleep. In addition, using portable EEG monitors, the distribution of REM and non-REM across the night can be assessed and compared between the summer and winter months, when sleep duration differs by about one hour per night. This research will identify the importance of temperature as a predictor of human sleep conditions, and begin to explain why sleep varies across the year in hunter-gatherer populations. These insights are important to better identify how our evolved sleep biology clashes with modern Western conditions, and how that clash may increase the risk of various sleep pathologies. They are also important first steps towards better understanding some of the adaptive challenges that faced early human ancestors as they transitioned from sleeping in trees in tropical climates, like chimpanzees, to the patterns of sleep conditions seen today.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
