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Polysomnography

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Contents of this page:

Illustrations

Sleep studies
Sleep studies

Alternative Names    Return to top

Sleep study; Polysomnogram; Rapid eye movement studies

Definition    Return to top

Polysomnography is a sleep study. It measures your sleep cycles and stages by recording brain waves (EEG), electrical activity of muscles, eye movement, breathing rate, blood pressure, blood oxygen saturation, and heart rhythm.

A specially trained health care provider will directly observe you while you sleep.

There are two states of sleep: non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep.

REM sleep is associated with dreaming. Your body muscles (except your eyes and lungs) do not move during this stage of sleep.

NREM sleep has four stages distinguishable by EEG waves.

REM sleep alternates with NREM sleep approximately every 90 minutes. A person with normal sleep usually has four to five cycles of REM and NREM sleep during a night.

How the Test is Performed    Return to top

Polysomnography is usually done in a sleep study center. You will lie on a bed in the test center. The test may be carried out during the night so that normal sleep patterns can be studied. The health care provider will place electrodes on your chin, scalp, and the outer edge of your eyelids. These must remain in place while you sleep.

Signals from electrodes are recorded while you are awake with your eyes closed and during sleep. The time taken to fall asleep is measured as well as the time to enter REM sleep.

Monitors to record your heart rate and breathing will be attached to your chest.

In some sleep study centers, a video camera records your movements during sleep.

How to Prepare for the Test    Return to top

Do not take any sleeping medication and do not drink alcohol or caffeine-containing beverages before the test.

Why the Test is Performed    Return to top

The test is done to diagnose possible sleep disorders, including:

Normal Results    Return to top

A normal test result shows usual or normal patterns of brain waves and muscle movements during sleep.

What Abnormal Results Mean    Return to top

Abnormal results may confirm a suspected sleep disorder.

Update Date: 5/22/2007

Updated by: Joseph V. Campellone, M.D., Division of Neurology, Cooper University Hospital, Camden, NJ. Review provided by VeriMed Healthcare Network.

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