UCLA

Sleep is broadly conserved across the animal kingdom but can vary widely across species. It is currently unclear which selective pressures and sleep regulatory mechanisms influence differences in sleep between species. The fruit fly Drosophila melanogaster has become a successful model system for examining sleep regulation and function, but little is known about the sleep patterns and need for sleep in many related fly species. Here, it is shown that fly species that have adapted to extreme desert environments, including D. mojavensis, exhibit strong increases in sleep compared to D. melanogaster. Long-sleeping D. mojavensis show intact sleep homeostasis, indicating that these flies may carry an elevated need for sleep. Additionally, D. mojavensis exhibit altered abundance or distribution of several sleep/wake-related neuromodulators and neuropeptides that are consistent with their reduced locomotor activity and increased sleep. Finally, in a nutrient-deprived environment, the sleep patterns of individual D. mojavensis are strongly correlated with their survival time and disrupting sleep via constant light stimulation renders D. mojavensis more sensitive to starvation. These results demonstrate that D. mojavensis is a novel model for studying organisms with high sleep need, and for exploring sleep strategies that provide resilience in extreme environments.