Researchers from Washington State University explored how bears manage metabolism and circadian rhythms during hibernation, publishing their findings in a respected journal, the Journal of Comparative Physiology B (JCPB) [Citation: Journal of Comparative Physiology B].
Circadian rhythms describe the daily cycles that shape the physiology of most living beings on Earth. These internal clocks are closely tied to metabolism. When people experience long-term disruptions to their sleep-wake patterns, such as night shift work, they often encounter metabolic challenges like weight gain and an increased risk of diabetes.
To understand how bears survive long periods of dormancy without succumbing to diabetes or bone loss, researchers examined how the body adapts to a winter lifestyle that features extended sleep followed by renewed activity. The aim was to uncover how a creature can endure months without food while maintaining essential bodily functions that depend on circadian timing.
In laboratory simulations, the team analyzed bear cells at approximately 34°C to represent the slowed state of hibernation and 37°C to reflect the active season. They found that thousands of genes continue to operate in a balanced energy rhythm even when tissues slow down. In effect, the organism keeps its circadian timing in play, producing energy gradually across the day rather than in bursts, which helps conserve resources during dormancy.
The energy cost of maintaining circadian rhythms is real. The researchers propose that by modulating this rhythm during hibernation, bears can draw on a portion of the energy associated with the circadian system while spending far less fuel overall. This adaptation could be a key factor allowing bears to endure months without food while staying healthy enough to wake and travel when spring arrives.
As one of the study’s leading researchers explained, the comparison is helpful: it is like adjusting a thermostat. When energy conservation is needed, the thermostat is dialed back, yet the biological clock itself does not shut off. What emerges is a refined control of metabolism — a new way for an animal to fine-tune energy use without sacrificing vital functions.
These insights complement a broader body of work that links sleep, metabolism, and cardiovascular health in humans. Scientists continue to ask how circadian alignment can influence long-term health outcomes and what practical lessons can be drawn from the bear’s strategy for managing energy during periods of scarcity. The research underscores the idea that rhythmic biological processes, when understood and respected, play a crucial role in how organisms adapt to environmental stress and resource limitations. [Citation: Journal of Comparative Physiology B]
In sum, bear hibernation reveals a sophisticated orchestration of sleep, energy, and physiological resilience. Rather than simply slowing down, the bear’s system preserves a coherent circadian framework that guides energy production and consumption throughout the dormant phase. This balance helps the animal weather months of fasting and cold, preparing it to resume normal life when conditions improve. The findings offer a compelling example of how studying animal biology can illuminate principles that may one day inform human health strategies around sleep, metabolism, and longevity.