Hibernation

Hibernation is a deep sleep that helps animals survive winter. When food is hard to find, some animals slow their bodies way down. Their heart beats very slowly and they barely breathe. They live off fat stored in their bodies.

How Hibernation Works

Before winter, animals eat a lot of food to build up fat. When they hibernate, their body temperature drops very low. Their heart rate slows down a lot. Some animals barely breathe during hibernation.

Animals That Hibernate

Bears are the most famous hibernators. Ground squirrels, chipmunks, and woodchucks also hibernate. Some frogs even freeze almost solid during winter and thaw out in spring! Bats hibernate in caves and attics.

Fun Facts

• A hibernating groundhog's heart beats only 5 times per minute instead of 80.
• Some bears can hibernate for up to 7 months without eating or drinking.
• Wood frogs can survive being frozen almost solid during winter.

Did You Know?

Bears do not truly hibernate the way smaller animals do. They enter a lighter sleep called torpor and can wake up more easily if disturbed.