At WiseGEEK, we're committed to delivering accurate, trustworthy information. Our expert-authored content is rigorously fact-checked and sourced from credible authorities. Discover how we uphold the highest standards in providing you with reliable knowledge.

Learn more...

Are Bears True Hibernators?

Bears are often depicted nestled in dens, sleeping away the winter months. But are they true hibernators? Unlike some creatures that enter a deep, unyielding slumber, bears experience a lighter state of dormancy. Their body temperature drops modestly, and they can awaken if disturbed. Intrigued by how bears spend their winters? Join us as we uncover the mysteries of bear hibernation.

Somewhere along the way, you may have been taught that bears hibernate during the winter. Technically, that’s not quite correct. Rather than hibernating, bears go into an inactive state called torpor, where many of the same physiological changes take place. Their heart rate, breathing and brain wave activity slow down significantly, as they conserve energy in the cold winter months when food is in short supply. Bears can wake suddenly from torpor if they sense danger, and females can give birth and then go right back into this uber-restful state.

All about hibernation:

  • A hibernating animal’s metabolic rate slows to as low as 2 percent of normal levels and body temperatures can drop significantly. These changes don't occur during regular sleep.

  • Some animals hibernate for months at a time, including squirrels, lemurs, chipmunks, mice, groundhogs, lizards, snakes, and bats. Migrating birds may enter torpor to save energy before long flights.

  • During torpor, bears recycle their own urea (a byproduct of urine), and use water from their body fat, which allows them to stay hydrated.

You might also Like

Discussion Comments


Urea is not a byproduct of urine, but is produced in the tissues as a waste of product of protein metabolism. Its relationship with the urine is that that is its main route of excretion.

Secondly, the body fat has no water in it at all. Water however can be produced from fat as a end product when it is aerobically metabolized in a biochemical process known as the Cycle of Krebs.

Post your comments
Forgot password?
    • Bears don't hibernate; in winter, they enter a deep sleep called torpor but can wake easily if hurt or threatened.
      By: kcxd
      Bears don't hibernate; in winter, they enter a deep sleep called torpor but can wake easily if hurt or threatened.