A state in which certain animals cease their normal activities and enter a period of dormancy during the winter months, often characterized by a significant reduction in metabolic processes. This behavior is observed in small mammals such as hedgehogs, squirrels, and dormice, but also applies to insects and various cold-blooded species like frogs and snakes.

The physiological adaptation of various animals, including bears and snakes, to survive through the winter by lowering their body temperature and entering a sleep-like state, during which they do not eat or engage in regular behaviors, but may awaken periodically for essential functions like excretion.

A survival strategy employed by several species to cope with harsh winter conditions, enabling them to conserve energy and emerge in spring when temperatures rise and food becomes available, thereby enhancing their chances of survival.