Mapping sleep behavior in a society of insects: Spatial and temporal analysis of worker honey bee sleep

If situated in a perpetually bustling society, where and when do individuals sleep? Honey bees (Apis mellifera) are known to exhibit sleep behavior, and face variables such as age and position of resources within their hive that may impact their sleep schedule, both spatially and temporally. We introduced individually marked, recently eclosed worker honey bees into an observation hive, and mapped bees’ temperature and sleep behavior as they aged and changed tasks. We also produced maps of the hive’s comb contents as the colony grew and the contents changed. Bees exhibited a state of relative immobility while discontinuously ventilating (correlated with highest arousal threshold, one of the hallmarks of sleep) during each stage of adult life. The youngest worker bees (cell cleaners) slept exclusively inside cells, preferred to sleep closer to the edge of the hive, and slept near uncapped brood. The eldest adults (foragers) slept outside cells, on the edge of the hive, away from uncapped brood, and primarily at night. When asleep, foragers’ temperature decreased, and did not differ between day and night or with respect to location in the hive. Understanding where and when different castes within a society sleep is the starting point from which to understand sleep and its impact on the behavior and ecology of societies, and the societally-based purpose(s) of sleep. Thermal maps may be a means by which we can predictably assess sleep across a society of insects.