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).
Cycles. Sleep does not progress through all of these stages in sequence, however. Sleep begins in Stage One and progresses into stages 2, 3, and 4. Then, after Stage Four sleep, Stages Three, then Two are repeated before going into REM sleep. Once REM is over, we usually return to Stage Two sleep. Sleep cycles through these stages approximately 4 or 5 times throughout the night. We typically enter REM approximately 90 minutes after falling asleep. The first cycle of REM often lasts only a short amount of time, but each cycle becomes longer. This is why we need long periods of sleep each night. If we get short periods of sleep, we canât really get through the stages we need to heal and stay healthy. REM can last up to an hour as our sleep progresses. In case you are wondering, if you feel like a dream is taking a long period of time, it really is. Contrary to what was once believed, dreams take as long as they actually seem.