Temperature-dependent sleep patterns in Drosophila

Sleep is a fundamental physiological process conserved through evolution, from worms to humans. Understanding how temperature influences sleep is essential for comprehending the complexities of animal behavior, physiology, and their adaptations to thermal environments. This study explores the impact of temperature on sleep behavior and patterns in Drosophila melanogaster. Through a comprehensive analysis, we assessed how temperatures during development and adulthood affect sleep duration and fragmentation. Our results show that exposure to non-optimal temperatures increases overall sleep duration, primarily by extending daytime sleep. Sleep patterns were also substantially modulated by developmental temperature. Flies that developed at 29 °C exhibited longer sleep durations compared to those that developed at either 19 °C or 25 °C. In general, sleep was more prevalent than wakefulness under most conditions, particularly at non-optimal temperatures. At intermediate temperatures, sleep became more fragmented and episodes shorter. The interplay between sleep and wakefulness varied depending on both population and developmental temperature. Developmental and adult temperatures also influenced sleep latency, the time it takes to fall asleep. Interestingly, the impact of temperature on daytime sleep latency differed among populations, whereas nighttime sleep latency consistently increased with temperature for all groups. Flies that developed at 29 °C showed shorter sleep latencies than those from other temperatures, both during the day and night. Finally, a strong negative correlation was observed between total sleep duration and daily locomotor activity across all groups and temperatures. These findings underscore the critical role of environmental temperature in regulating sleep behavior in Drosophila, with potential implications for understanding temperature-dependent sleep mechanisms in other organisms.