Winter Hibernation in Animals: From Physiological Adaptation to Metabolic Miracle Winter hibernation (hibernation) is not just a long sleep, but a complex and radical survival strategy, representing one of the most extreme physiological states in the animal kingdom. It is a deeply regulated state of life function inhibition, allowing survival through periods of food scarcity and low temperatures with minimal energy expenditure. Its study is at the forefront of biomedicine, as it opens up prospects for cryobiology, space medicine, and the treatment of critical conditions in humans. 1. Key Physiological Parameters of Hibernation. The main goal of hibernation is to reduce energy consumption by 85-99% compared to wakefulness. This is achieved through a cardinal restructuring of the entire body's work: Metabolism: The rate of metabolism drops to 2-5% of the norm. The source of energy is not glucose, but fatty acids stored in brown and white adipose tissues. Brown adipose tissue, rich in mitochondria, is particularly important for non-shivering thermogenesis upon awakening. Body Temperature: In true hibernators (such as squirrels, groundhogs, hedgehogs, bats), body temperature (Tt) drops to values close to the ambient temperature (To), often +1…+5°C, and in some species even below 0°C (the Arctic groundhog can tolerate Tt up to -2.9°C). This state is called heterothermy. Respiration and Heartbeat: The heart rate of the groundhog drops from 100-200 to 3-5 beats per minute. Breathing becomes rare and irregular: apneas between breaths can last from several minutes to an hour or more. Nervous System: Despite deep suppression, the brain retains the ability to control the state and trigger periodic awakenings — short episodes of returning to euthermia (normal temperature) every 1-3 weeks. The reasons for these awakenings are not fully clear (presumably, the need to restore homeostasis, activation of the immune system), and they consume up to 80% of all winter energy. 2. Molecul ... Read more