PROJECT SUMMARY Sleep loss is increasingly recognized as a significant risk factor in numerous metabolic diseases such as diabetes, obesity, metabolic syndrome, cancer, and cardiometabolic disorders. Clinical and model studies have confirmed negative metabolic effects of sleep loss. Intriguingly, sleep loss also dampens peripheral rhythms in human populations, which raises the question of whether the metabolic-sleep connection is mediated through circadian rhythms. Time-dependent analysis of metabolic changes has revealed large-scale oscillations in metabolite pools through the course of the circadian day in humans and other model systems such as rodents and flies. Disruption of the molecular clock, either genetically or through dietary intervention such as high-fat diet or mis-timed restricted feeding, causes insulin resistance and a lack of so-called `metabolic flexibility', phenotypes shared with sleep loss. We hypothesize that effects of reduced sleep on metabolism are mediated through changes in rhythms of energetic and redox metabolic pathways. One major limitation in gleaning mechanistic understanding of the sleep-circadian-metabolism connection is difficulty in measuring metabolic flux at different times of day in vivo. Our team has developed an innovative model of circadian flux using Drosophila melanogaster (fruit fly). Furthermore, dietary manipulations, such as time-restricted feeding in the active period or caloric restriction, maintain amplitudes in metabolic cycles in face of circadian disruption and have been associated with cardio-metabolic health in flies. In this proposal, we will exploit the genetic flexibility of D. melanogaster to test the above hypothesis in the following related but independent aims: ? Aim 1: Determine the impact of sleep loss on metabolic rhythms. Impact: An impact of sleep loss on metabolic oscillations will clarify the approach towards understanding how circadian rhythms and sleep, each of which is currently studied independently, affect metabolism. ? Aim 2: Determine if nutritional challenge exacerbates the metabolic effects of sleep loss in a time-of- day specific manner. Impact: These studies will provide direct mechanistic insights into the origin of metabolic imbalance which has only been inferred in studies to date. Future pharmacological or behavioral interventions can be targeted accordingly. ? Aim 3: Determine if time-restricted feeding can mitigate effects of sleep deprivation on metabolism. Impact: Demonstration that dietary manipulation mitigates negative metabolic consequences of sleep loss has the potential for interventional applicability in at risk real-world human populations.