Claudia Valeggia and Eduardo Fernandez-Duque, in collaboration with H. de la Iglesia (University of Washington) have recently been awarded an NSF grant for continuing their studies of Ancestral Sleep. In a recent publication they showed that communities of the traditionally hunter-gatherer Toba/Qom of Argentina living under natural daylight have an earlier beginning of sleep and a one-hour longer daily sleep bout than similar communities with free access to electric light (de la Iglesia et al. 2015). In this new project they will examine the biological mechanism behind this difference in sleep timing by determining the timing of release of the hormone melatonin in the two Toba/Qom populations. They will also evaluate the influence that moonlight has in sleep timing and consolidation in communities with and without access to electric light.