十万个为什么·科学启蒙30篇（2）

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为什么一些动物会冬眠？

Hibernation is not just deep sleep — it’s a controlled state of metabolic slowdown that helps animals survive food shortages and extreme cold.
During hibernation, heart rate drops from 80 to as few as 5 beats per minute, and body temperature falls close to ambient levels.
Bears lower their metabolism by 75%, yet unlike smaller mammals, they don’t eat, drink, urinate, or defecate for months.
Their bodies recycle waste products: urea is converted back into proteins to prevent muscle loss — a trick scientists hope to adapt for human medicine.
True hibernators like ground squirrels enter torpor so deeply that they must shiver intensely to warm up again — a process taking hours.
Not all cold-season dormancy counts as hibernation; some frogs freeze solid and thaw unharmed thanks to natural antifreeze proteins in their blood.
Climate change is disrupting hibernation timing, causing mismatches between emergence and food availability — threatening survival.
Studying hibernation could lead to breakthroughs in treating obesity, diabetes, and long-duration space travel.