Like any other animal, Drosophila sleeps. But some individual flies hardly rest at all, according to a study published yesterday (February 20) in Science Advances. And results from a sleep deprivation experiment show that, in contrast to the devastating effects seen among other animals when they are kept awake, fruit flies handle it pretty well.
“[W]e report two surprising findings . . . challenging the notion that sleep is a vital necessity: the discovery of virtually sleepless flies and the finding that chronic sleep restriction in Drosophila melanogaster has notably less pronounced effects on longevity than previously thought,” the authors write in their paper.
For one part of the project, the researchers videotaped fruit flies behaving in the lab for four days and had a machine-learning program calculate the time the flies were moving or were still, presumably asleep. Typically, the flies slept several hours, but there was great variation among individuals, with some consistently sleeping only a few minutes each day. “[F]lies (and, in fact, animals) sleeping as little as few minutes a day were never identified before,” the authors write.
To see how flies would fare if they were forced to stay awake, the researchers rigged a tube so that it would spin if the fly settled down, thereby flipping it over and nudging it awake. This went on for the duration of the flies’ lives. Again, surprising results: sleep-deprived males lived just as long as unperturbed males, while sleep-deprived females lived slightly shorter lives, 37.5 days on average compared with 41 days among female flies allowed to sleep.
In prior sleep-deprivation studies in other species, the disturbance typically led to early death.
“It’s not that there are no consequences to not sleeping—in fact we will be investigating the effects on mental performance in flies in future experiments—but our study has made us question whether sleep deprivation alone causes death,” says coauthor Giorgio Gilestro of Imperial College London in a press release.
See “Go to Bed!”
According to The New York Times, the study questions the universality of the need to sleep, although the research has its limitations. For one, the experimenters only tested one strain of Drosophila. And Amita Sehgal, a sleep researcher at the University of Pennsylvania who was not involved in the study, questions whether the flies’ micromovements that had been tallied as waking periods may have in fact represented sleep, although the authors are convinced they were not waking behaviors.