Journal Article

Sleep deprivation suppresses aggression in Drosophila

Mainwaring, Benjamin, Yue, Zhifeng, Sehgal, Amita, Kayser, Matthew S

2015

Overview

Sleep disturbances negatively impact numerous functions and have been linked to aggression and violence. However, a clear effect of sleep deprivation on aggressive behaviors remains unclear. We find that acute sleep deprivation profoundly suppresses aggressive behaviors in the fruit fly, while other social behaviors are unaffected. This suppression is recovered following post-deprivation sleep rebound, and occurs regardless of the approach to achieve sleep loss. Genetic and pharmacologic approaches suggest octopamine signaling transmits changes in aggression upon sleep deprivation, and reduced aggression places sleep-deprived flies at a competitive disadvantage for obtaining a reproductive partner. These findings demonstrate an interaction between two phylogenetically conserved behaviors, and suggest that previous sleep experiences strongly modulate aggression with consequences for reproductive fitness. We know from personal experience that sleepless nights can change the way we behave, sometimes making us more irritable and less adept at social interactions. However, it can be difficult to establish cause and effect: does a lack of sleep lead to altered behavior, or vice versa? The fruit fly, Drosophila melanogaster, is a popular model organism for studying questions like this because its neural circuitry is relatively well understood. To explore the effects of lack of sleep on social behaviors, and in particular on aggression, Kayser et al. disrupted the sleep of male fruit flies using various techniques, such as shaking them during the night, and then observed how they behaved. The experiments revealed that sleep-deprived flies were less aggressive than flies with undisturbed sleep. Furthermore, sleep-deprived male flies were less successful at mating with female flies when they were in direct competition with a rested male fly. Normal behavior was restored when the sleep-deprived flies were allowed to recover lost sleep for as little as six hours before the next aggression assay. To investigate how sleep loss leads to a decrease in aggressive behavior, Kayser et al. used different drugs to treat the sleep-deprived flies. A drug activating the equivalent of the noradrenergic system in flies helped them to recover normal fighting behaviors despite a lack of sleep. In mammals, noradrenaline is a chemical that affects heart rate, sleep-wake patterns, aggression and a number of other phenomena. Although aggressive behavior is often perceived as negative in humans, it can be important for survival. Human brains and behaviors are obviously more complex than those of Drosophila. However, learning more about the neuronal circuits that control sleep and social behavior in fruit flies may lead to an improved understanding of these phenomena in humans and, in the longer term, the development of drugs that can influence or modulate aggressive behaviors.

• Publisher: eLife Sciences Publications Ltd,eLife Sciences Publications, Ltd
• Subject: Aggression / Aggressiveness / Animal reproduction / Animals / Behavior / Dopamine / Drosophila / Drosophila - physiology / Experiments / Food / Insects / Males / Medicine / Neuroscience / Octopamine / Octopamine - metabolism / Phylogeny / Reproductive fitness / Signal Transduction / sleep / Sleep Deprivation