Author response: Circadian photoreceptor CRYPTOCHROME promotes wakefulness under short winter-like days via a GABAergic circuitry

eLife AssessmentWinter months with short days are commonly associated with seasonal depression and hypersomnolence; the mechanisms behind this hypersomnolence however, remain unclear.Chen and colleagues identify a genetic basis for this phenomenon in the fly Drosophila -mutations in the circadian photoreceptor cryptochrome resulted in increased sleep under short photoperiods.These findings are valuable insights into the genetic mechanisms regulating sleep under short days.The data supporting the precise neurobiological basis of these effects however, remains incomplete.