Researchers from the Perelman School of Medicine at the University of Pennsylvania recently found that
sleep deprivation reduces aggression in fruit flies and affects their reproductive fitness. The team also
identified a related molecular pathway that might govern recovery of normal aggressive behaviors. The
work was published in eLife.
Matthew Kayser, MD, PhD, an assistant professor of psychiatry and the team focused on several
chemicals that have been associated with aggression in fruit flies and other species. “There has been a
lot of work on these monoamines, the same ones that are potentially involved in some aspects of
mammalian aggression,” Kayser says in a release. “We asked what happens if we try to activate
dopamine receptors or octopamine, a type of monoamine, after sleep loss in flies.”
“If you activate octopamine receptors, you rescue the fighting behavior,” Kayser says. “The other drug L-
DOPA makes them really active, but they’re not fighting.” Neither drug affected fighting behaviors when
flies were not sleep deprived. Kayser notes that the relative simplicity of the fruitfly model compared to
working with mammals is a more direct approach to studying the sleep-aggression link. “We first sleep
deprived the flies and looked at their fighting behavior, and saw a huge, very clear effect on behavior,”
he says.
“Suddenly they go from fighting quite a bit to sharing resources and not fighting much.” Kayser and his
colleagues also studied the effects of reduced aggression on social behavior, specifically reproductive
behavior and success. “We asked the simple question, ‘Does sleep deprivation affect sexual fitness?’”
The answer was yes: Reduced aggressiveness of the sleep-deprived male flies clearly impaired their
mating success when competing with non-sleepy males for females.
