hibernation

State of dormancy in which certain animals spend the winter. It is associated with a dramatic reduction in all metabolic processes, including body temperature, breathing, and heart rate.

The body temperature of the Arctic ground squirrel falls to below 0°C/32°F during hibernation. Hibernating bats may breathe only once every 45 minutes, and can go for up to two hours without taking a breath.

A species of lemur, cheirogaleus medius, was the first primate found to hibernate through winter. Unlike other species that hibernate, dormant lemurs do not regulate their body temperature, which instead closely follows the ambient temperatures of their tree-hole homes.