Investigating a sleep-promoting circuit across the lifespan in drosophila melanogaster

The National Institute of Neurological Disorders and Stroke awarded The Trustees of The University of Pennsylvania $100,228 on December 1, 2026, to investigate a sleep-promoting circuit across the lifespan in Drosophila melanogaster under the Extramural Research Programs in the Neurosciences and Neurological Disorders program (CFDA 93.853).

The project characterizes how sleep-regulating neural circuits function in fruit fly larvae and whether those circuits persist and maintain their organization into adulthood. A large-scale neural activation screen identified approximately 20 neurons marked by R76G11-GAL4 that promote sleep in larvae. Preliminary data indicate that a subset of these larval neurons matures into ellipsoid body ring neuron subtypes previously implicated in adult sleep regulation. The research tests the hypothesis that R76G11+ neurons promote sleep across the lifespan but operate through distinct circuits in early life versus adulthood, with the goal of characterizing the larval sleep-promoting circuit and determining whether it functions in mature flies.

The work is motivated by evidence that sleep changes developmentally, with greater sleep duration, depth, and drive early in life when critical neurodevelopmental periods occur. Inadequate sleep during this developmental window can cause cognitive deficits in children and exacerbate symptoms of neurodevelopmental disorders, suggesting sleep plays a pivotal role in brain maturation. While sleep circuits have been extensively studied in adult flies, they remain largely unexplored in larvae, and the genetic regulation of sleep differs between juvenile and mature periods across species, but a circuit-level perspective on this change has not been explored.

Work is performed in Philadelphia, Pennsylvania, with a period of performance through July 31, 2029. This is a project grant, an assistance type that funds investigator-initiated research.

Abstract

Sleep changes through development, such that sleep duration, depth and drive are greater early in life compared to adulthood. This increased propensity for sleep in early life coincides with critical periods of neurodevelopment. Inadequate sleep during this time can result in cognitive deficits in children, as well as an exacerbation of symptoms in children with neurodevelopmental disorders, suggesting that sleep plays a pivotal role in brain maturation. However, little is known regarding how sleep is regulated in early life. The fruit fly, drosophila melanogaster, is a powerful model to investigate sleep-regulating mechanisms across the lifespan, as both larval and adult quiescent states share many characteristics with mammalian sleep. While sleep circuits have been extensively studied in adult flies, they remain largely unexplored in larvae, and IT is unknown whether sleep circuits maintain their organization to regulate sleep across the lifespan. There is accumulating evidence across species that the genetic regulation of sleep is different in juvenile versus mature periods, but a circuit perspective on such sleep regulatory change has not been explored in any system. The goal of this proposal is to characterize a larval sleep-promoting circuit and determine whether IT persists into adulthood and retains its logic and function. A large-scale neural activation screen identified a population of ~20 neurons defined by R76G11-GAL4 that promote sleep in larvae. Preliminary data show that a subset of these larval neurons matures into ellipsoid body ring (EB r) neuron subtypes which have been previously implicated in regulating sleep in adult flies. This project will test the hypothesis that R76G11+ neurons promote sleep across the lifespan, but act through distinct circuits in early life versus adulthood. First, the larval sleep-promoting circuit will be characterized by determining if R76G11+ neurons are necessary for larval sleep (aim 1A), which signaling molecule(s) these neurons use to promote sleep (aim 1B), and by defining key neurons downstream of the R76G11+ sleep cells (aim 1C). Then, IT will be determined if adult EB r neurons that correspond to the larval sleep neurons are sufficient (aim 2A) and necessary (aim 2B) for sleep in adult flies. Further, the hypothesis that adult EB r neurons use a distinct circuit architecture to regulate adult sleep compared to larval stages will be tested (aim 2C). Findings from this project will advance our understanding of how sleep is regulated in early stages of development and reveal whether sleep-promoting circuit organization changes across the lifespan.