Plasticity in a Drosophila wing circuit supports an adaptive sleep function

Abstract

Sleep is a near universal phenomenon whose function remains controversial. An influential theory of sleep function posits that ecological factors that place animals in harms way increase sleep as a state of adaptive inactivity. Here we find that manipulations that impair flight in Drosophila increase sleep. Further, we identify a novel neural pathway from peripheral wing sensory neurons to the central brain that mediates the change in sleep. Moreover, we show that flight impairments activate and induce structural plasticity in specific projection neurons to support increases in sleep over days. Thus, chemosensory neurons do not only signal sensory cues but also appear to provide information on wing-integrity to support behavioural adaptability. Together, these data provide mechanistic support of adaptive increases in sleep and highlight the importance of behavioural flexibility for fitness and survival.