The term for the period when an animal is dormant is "hibernation." Hibernation is a state of reduced metabolic activity that some animals enter during cold months or when food is scarce. During this period, the animal's heart rate, breathing, and body temperature significantly decrease, allowing it to conserve energy. Hibernation is common among mammals such as bears and ground squirrels, but some reptiles and amphibians also enter a form of dormancy called brumation. This adaptation helps animals survive in harsh environmental conditions until favorable conditions return, when they can resume their normal activities.