There are five stages of sleep, according to the National Sleep Foundation, four non-REM stages and REM (rapid eye movement) sleep, and sleepers cycle through the stages about every 90 to 100 minutes.
Stage 1 is the transitional stage, when you’re between waking and sleep. Your brain waves and muscle activity slow. Sometimes people’s bodies jerk just before they fall asleep.
Stage 2 is a light sleep stage. Eye movements cease. Body temperature drops, and heart and brain activity slows. National Sleep Foundation NSF material says there are periods of muscle tone and muscle relaxation, and that occasional brain-wave spikes, called sleep spindles, occur during this stage of sleep.
Stages 3 and 4 are called delta sleep. These are the deep sleep stages, and this is when body restoration and repair occurs. Temperature drops even further during this phase, brain waves are slow and there is decreased muscle tone. sleep experts believe fibromyalgia may be associated with poor delta sleep. People woken during delta sleep are often groggy and disoriented. Night terrors occur during this sleep stage.
Stage 5 is REM sleep, a period of fast brain waves; rapid, shallow breathing; and the rapid eye movements it’s named for. Dreaming, believed to be a way of organizing the day’s experiences, occurs during REM sleep. Have you ever wanted to scream during a nightmare and been unable to? Muscles become temporarily paralyzed during REM.
Source: Cathy Frisinger, McClatchy Newspapers
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