An inactive state resembling deep sleep in which certain animals living in cold climates pass the winter. In hibernation, the body temperature is lowered and breathing and heart rates slow down. Hibernation protects the animal from cold and reduces the need for food during the season when food is scarce. Compare estivation.
Does Dreaming Indicate a Good Nightâs Sleep? Dreams are typically indicative of a good nightâs sleep, demonstrating that you have passed through the light sleeping phase (NREM) and entered into a deep sleep (REM).
Sleep is divided into two types: rapid eye movement (REM) and nonrapid eye movement (non-REM). REM and non-REM sleep alternate in 90- to 100-minute cycles. Most dreaming occurs during REM sleep. Nightmares usually occur in the middle of the night or early morning, when REM sleep and dreaming are more common.