Correlates of Sleep and Waking in <i>Drosophila melanogaster</i>

TLDR

Drosophila displays a circadian rest‑activity cycle, but it is unclear whether this rest constitutes sleep or merely inactivity. Rest in Drosophila behaves like mammalian sleep, exhibiting increased arousal thresholds, homeostatic regulation independent of the circadian clock, age‑ and drug‑dependent abundance, and modulation by monoamine catabolism pathways, indicating it can serve as a genetic model for sleep.

Abstract

Drosophila exhibits a circadian rest-activity cycle, but it is not known whether fly rest constitutes sleep or is mere inactivity. It is shown here that, like mammalian sleep, rest in Drosophila is characterized by an increased arousal threshold and is homeostatically regulated independently of the circadian clock. As in mammals, rest is abundant in young flies, is reduced in older flies, and is modulated by stimulants and hypnotics. Several molecular markers modulated by sleep and waking in mammals are modulated by rest and activity in Drosophila , including cytochrome oxidase C, the endoplasmic reticulum chaperone protein BiP, and enzymes implicated in the catabolism of monoamines. Flies lacking one such enzyme, arylalkylamine N -acetyltransferase, show increased rest after rest deprivation. These results implicate the catabolism of monoamines in the regulation of sleep and waking in the fly and suggest that Drosophila may serve as a model system for the genetic dissection of sleep.