A test of sleep cycles and stages through the use of continuous recordings of brain waves ( EEG ), electrical activity of muscles, eye movement (electrooculogram), respiratory rate, blood pressure , blood oxygen saturation, and heart rhythm and direct observation of the person during sleep. There are 2 states of sleep: non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep. REM sleep is associated with dreaming and generalized muscle paralysis sparing the eye muscles and diaphragm. NREM sleep has 4 stages distinguishable by EEG waves. REM sleep alternates with NREM sleep approximately every 90 minutes. A person with normal sleep usually has 4 to 5 cycles of REM and NREM sleep during a night.

Alternative Names

Sleep studies; Polysomnography; Rapid eye movement studies