Gandhi Yetish: University of New Mexico

Short
sleep duration is associated with numerous, sometimes severe, negative health outcomes, and yet many people report regularly sleeping insufficiently. Part of the challenge in improving poor health practice lies in the fact that a consensus definition of “good”
sleep remains lacking. In the scope of my dissertation research, I (with many collaborators) have sought to implement an evolutionary and ecological perspective to address this issue (in part). We argue that sleep is not only as a physiological state of being,
but as a behavior of sorts, regulated by shifting opportunity costs. In this talk, I will present three semi-independent studies that together test the hypothesis that sleep on any given night is a flexible phenotype (or reaction norm) that responds dynamically
to short-term needs. The first study presents findings from Yetish et al., 2015, which compares sleep among three independent small-scale societies (Hadza, San, Tsimane) to assess the degree to which post-industrial sleep patterns reflect a pathological shift
in chronic sleep patterns (answer: little, if at all). The second two studies present early findings from works-in-progress that test the effects on sleep from two different types of opportunity costs: productivity and vigilance. Using a mixture of accelerometry
(for objective sleep measurements) and quantitative ethnographic interviews (for behavioral insights), we investigated how the need to procure food and the degree of exposure in a sleeping site affect sleep patterns among Tsimane hunter-horticulturalists in
Amazonian Bolivia, and find support for the proposed opportunity cost tradeoff model of sleep optimization.