Longitudinal study of sleep and diurnal rhythms in Drosophila ananassae.

Mistiming of circadian rhythms impairs quality of life. The sleep fragmentation that results can lead to fatigue, mood alteration, and short-term memory problems. Unfortunately, this suite occurs in humans as we age. In the current study, we used high-resolution monitors to track how circadian patterns of locomotor activity change in female Drosophila ananassae as they enter mid-to-late life. This equipment is a more recent addition to the fly circadian field and has not been previously used for long-term activity tracking. At 2-3 days post-eclosion, D. ananassae were placed into climate-controlled vivariums for 60 days. Daily actograms were generated for each animal, along with a time series of activity across the observational period. Consistent with findings from older rodents and humans, older D. ananassae exhibited degraded patterns of wake and sleep that were fragmented-but still rhythmic-across the 24-h cycle. Overall levels of daily activity declined with age, with particular loss of circadian arousal in the wake-maintenance zone a few hours before bedtime. Interestingly, our high-resolution monitoring strategy was also able to document a sleep correlation previously associated with human aging in flies: displacement of sleep timing arising from possible changes in circadian and homeostatic regulation. Future experiments may determine whether the age-related impairments seen in the sleep-circadian system of D. ananassae can be mitigated through precision light treatment.