Danish scientists from the University of Copenhagen explored the molecular pathways that govern hibernation in both large and small mammals. The study appears in the scientific magazine eLife, contributing new insights into how animals orchestrate their energy use during long periods of inactivity.
During hibernation, animals dramatically slow their metabolism and rely on stored energy reserves. For a long time, researchers had only a vague picture of the cellular events taking place inside the bodies of animals in deep sleep. This work advances that understanding by comparing different species under natural hibernation-like conditions and examining how their bodies conserve energy when activity drops to a minimum.
The researchers used a range of mammals as models, including brown and black bears, ground squirrels, and dormice. A key finding is the important function of myosin, a muscle contraction protein, in regulating how energy is consumed during hibernation. This protein helps generate usable energy during the sleep-like state without triggering muscle tremors, enabling a controlled, low-energy mode of life for extended periods.
Among large hibernators, body temperature remains relatively stable throughout the torpor phase. In contrast, some smaller hibernators such as ground squirrels periodically interrupt their long sleep to eat or relieve themselves. Yet the primary energy-management mechanism during the winter rest appears to be the maintenance of skeletal muscles as a central heating system, ensuring that essential metabolic processes continue without high energy expenditure.
The study also observed that even in hibernation, circadian rhythms persist and influence energy use according to the time of day. Those internal clocks help coordinate when energy demands rise or fall, shaping how the animal balances needs with prolonged rest.