In the wild, polar bears spend between seven and eight hours each day resting or sleeping. They do this to conserve their energy and also to keep from freezing. They do this by curling up in a ball shape and using their outstretched paws as pillows. They also allow snow to pile up around them for more insulation. They may even snore while they sleep!
The polar bears sleep on snow drifts, ice floes, or rocky areas. They are also known to dig pits, which are temporary shelters for resting. These are similar to the dens that they hibernate in during the winter months. In zoos, polar bears may sleep on their daybeds or in a cave. During the summertime, they are most likely to sleep during the day and hunt at night. This shift is due to climate change, as the Arctic ice is slowly disappearing and traditional prey is harder to find.
When a polar bear does enter its hibernation den, she will dig into a gravel ridge or sand for a warm place to sleep. She will also scrape away ice from the ceiling of the den to ensure oxygen can flow into the space. This is why polar bears can survive for days in their dens during the hibernation process. However, they will die from oxygen deprivation if they do not emerge from their dens for days at a time to breathe fresh air and eat during this time.