Most sleep does not serve a vital function: Evidence from <i>Drosophila melanogaster</i>.

Abstract

Sleep appears to be a universally conserved phenomenon among the animal kingdom, but whether this notable evolutionary conservation underlies a basic vital function is still an open question. Using a machine learning-based video-tracking technology, we conducted a detailed high-throughput analysis of sleep in the fruit fly <i>Drosophila melanogaster</i>, coupled with a lifelong chronic and specific sleep restriction. Our results show that some wild-type flies are virtually sleepless in baseline conditions and that complete, forced sleep restriction is not necessarily a lethal treatment in wild-type <i>D. melanogaster</i>. We also show that circadian drive, and not homeostatic regulation, is the main contributor to sleep pressure in flies. These results offer a new perspective on the biological role of sleep in <i>Drosophila</i> and, potentially, in other species.