Hiberare

Hiberare, in biology often called hibernation, is a physiological state in which certain animals markedly reduce metabolism to endure periods of cold, food scarcity, or other environmental stress. The process involves lower body temperature, slowed heart rate, decreased respiration, and reduced activity, allowing energy conservation for extended periods. In true hibernation, animals enter sustained bouts of torpor with body temperatures approaching that of the environment and periodic arousals; seasonal torpor is a milder, more variable form of metabolic suppression that may not include deep cooling.

Triggers are primarily changes in day length and ambient temperature, signaling the approach of winter or resource depletion. Mechanisms include the use of stored fat reserves, greatly reduced energy expenditure, and, in some species, the activation of brown adipose tissue to generate heat during brief arousals.

Examples of hibernating animals include ground squirrels, marmots, hedgehogs, bats, and several small rodents. Bears, while entering a winter rest, are often described as a form of torpor rather than true hibernation because their body temperature remains relatively high and arousals occur less frequently.

Adaptations and significance: hibernation helps animals survive seasons with scarce resources, maintains energy balance, and can support subsequent growth and reproduction when conditions improve. In humans, interest lies in medical and spaceflight research exploring induced hypothermia and metabolic suppression, though humans do not naturally hibernate.