Normal sleep has 5 distinct states or phases: rapid eye movement (REM) sleep is when rapid eye movements occurs. This is associated with dreaming. During sleep, a person usually has about 4 or 5 periods of REM sleep, accounting for 20-25% of the sleep period. REM sleep is thought to be important for healthy restoration of the body as well as memory, mood, learning and anti-aging. Research shows that during illness, especially chronic illness, REM sleep can become decreased or even absent
which is associated with decreased ability of the body to recuperate, regenerate and a general feeling of wellness.