TED-ED: What's the difference between hibernation and sleep? - Sheena Faherty

The Arctic Ground Squirrel hibernates by burrowing under the permafrost and slipping into a state of suspended animation. The female black bear can give birth while she hibernates. The fat-tailed dwarf lemur prepares to hibernate by storing its fat reserves in its tail - doubling its body weight. Why do these animals go to such extremes? Sheena Lee Faherty details why animals hibernate.