Animals in very cold regions go into a state of inactivity or “sleep” to conserve energy during winter. This process is called __.

Some animals in very cold areas in the poles and temperate regions go into a dormant, inactive state similar to sleeping during winters. This is called hibernation. During hibernation, these animals reduce their heart and breathing rates, lower their body temperatures and enter a state of inactivity in underground holes and tree holes. This conserves energy which otherwise would have been spent on heating up the body during cold winters. In these areas food is very scarce in winter, so animals cannot obtain sufficient energy to be active. Thus, they rely on hibernation to survive harsh winters.

Hibernation is done by polar bears, squirrels, hedgehogs, mice and even bats.