an adaptation of certain mammals that enables them to survive the unfavorable food and climatic conditions during the winter. Winter sleep is characteristic of some mammals, such as the bear, raccoon, badger, and hamster. In contrast to hibernation, winter sleep is characterized by a lesser decrease in body temperature and metabolic activity. The sleeping animal can change quickly to energetic activity. For the period of winter sleep, animals accumulate fat and move into burrows or other well-protected shelters; during this time they do not eat.