Abstract

Sleep ontogeny, or the growth of sleep behaviour across a lifespan, is an enduring feature of evolution. Studies on mammals have revealed that, in addition to having longer sleep intervals, early life sleep differs significantly from adult sleep in terms of its many sleep stages. It is unclear how intrinsic sleep output circuit maturation affects the development of sleep. Between juvenile and adulthood, the fruit fly Drosophila melanogaster experiences a variety of sleep-related alterations. Here, we study the differences between the sleep architecture of juvenile and mature flies using a non-invasive probabilistic method. The main cause of increased sleep in young flies is a lower likelihood of waking up, which is accompanied by longer periods of deeper sleep. Sleep-promoting neurons in the dorsal fan-shaped body (dFB) have been functionally altered, and this research suggests that these neurons regulate sleep differently in juvenile and older flies. The genes involved in the maturation of the dFB sleep circuit are implicated by transcriptomic analysis of dFB neurons at various ages and a subsequent RNAi screen. These findings indicate that alterations in sleep across the lifetime are influenced by the changing transcriptional statuses of sleep output neurons.

Keywords: Sleep; Drosophila; Ontogeny development