Behavioral and Genetic Features of Sleep Ontogeny in Drosophila.

The fruit fly Drosophila melanogaster, like most organisms, exhibits increased sleep amount and depth in young compared to mature animals. While the fly has emerged as a powerful model for studying sleep during development, qualitative behavioral features of sleep ontogeny and its genetic control are poorly understood. Here we find that, in addition to increased sleep time and intensity, young flies sleep with less place preference than mature adults, and, like mammals, exhibit more motor twitches during sleep. In addition, we show that ontogenetic changes in sleep amount, twitch, and place preference are preserved across sleep mutants with lesions in distinct molecular pathways. Our results demonstrate that sleep ontogeny is characterized by multifaceted behavioral changes, including quantitative and qualitative alterations to sleep as animals mature. Further, the preservation of sleep ontogenetic changes despite mutations that alter sleep time suggests independent genetic control mechanisms for sleep maturation. Statement of Significance Our data combining high-resolution behavioral tracking with video monitoring in Drosophila provide novel insight into sleep during early development, revealing conserved features of sleep in young animals. Our findings support the idea that genes regulating sleep ontogeny are distinct from those that regulate overall sleep duration. Deepening our understanding of early life sleep is highly relevant towards studying the function for sleep in the developing brain.