Sleep as an adaptation for energy conservation functionally related to hibernation and shallow torpor.
D000222:Adaptation, Physiological; D000818:Animals; D001833:Body Temperature Regulation; D004594:Electrophysiology; D004734:Energy Metabolism; D004956:Estivation; D006605:Hibernation; D006801:Humans; D012890:Sleep / Q000502:physiology*; D012895:Sleep, REM / Q000502:physiology