Synthetic human hibernation will likely require body temperatures warmer than those observed in traditional Holarctic hibernators. Dwarf lemurs (Cheirogaleus medius), a tropical primate capable of months-long hibernation, hibernate at relatively warm temperatures in Madagascar and the closest human relatives to humans able to do so. Therefore they are a valuable model to understand the energetic costs and savings of tropical thermoregulation. We hypothesized that hibernating at warm temperatures would allow for more regular, frequent interbout arousals, but at the cost of shorter torpor bouts and therefore lower energetic savings. To quantify the tradeoffs of tropical, warm hibernation and cooler conditions typical of higher-latitude hibernators, we housed captive dwarf lemurs in either a fluctuating warm environment that allowed for passive rewarming or a cooler, more constant environment that necessitated active, energetically-expensive arousals. Our research group is the first to replicate this hibernation phenotype in a lab setting while simultaneously measuring skin temperature and metabolic rate throughout the hibernation season. We found that dwarf lemurs in the fluctuating environment (12-32°C), had more frequent interbout arousals and lost weight at a faster rate than those lemurs housed in the more constant environment (16-19°C, p< 0.05). However, the energetic cost of each interbout arousal was significantly lower for animals in the warmer, fluctuating environment because animals were able to passively rewarm during daily temperature increases (p< 0.05). Conversely, those in the cooler environment displayed longer torpor bouts interspersed with fewer interbout arousals, but each arousal required substantially greater energetic expenditure. Our findings suggest that while hibernation at low temperatures may provide greater energetic savings, hibernation at warmer temperatures may offer enhanced homeostatic control through more frequent, less energetically-expensive interbout arousals. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.
Breit et al. (Fri,) studied this question.