Polysomnogram

Injury	Disease	Nutrition	Poison

Symptoms	Surgery	Test	Special Topic

Sleep studies

Overview

Risks

Results

Polysomnogram

Definition:

A polysomnograph is a test of sleep cycles and stages through the use of continuous recordings of brain waves (EEG), electrical activity of muscles, eye movement (electrooculogram), breathing rate, blood pressure, blood oxygen saturation, and heart rhythm and direct observation of the person during 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 and paralysis of body muscles (except for the eye and diaphragm muscles). 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.

Alternative Names:

Sleep studies; Polysomnography; Rapid eye movement studies

How the test is performed:

Polysomnograms are usually conducted 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 reproduced. Electrodes are placed on the chin, the scalp, and the outer edge of the eyelids in preparation for the test.

Characteristic patterns from the 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. Sometimes the movements of a person during sleep are recorded by video camera.

How to prepare for the test:

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

How the test will feel:

Electrodes will be placed on the skin and scalp. Monitors to record heart rate and breathing rate will be attached to the chest. Sometimes other test to determine breathing disorders during sleep are also performed.

Why the test is performed:

The test is performed to evaluate possible sleep disorders, such as insomnia, hypersomnia, excessive daytime sleepiness, obstructive sleep apnea, narcolepsy, breathing difficulties during sleep, behavior disturbances during sleep, or other sleep disorders.

Review Date: 7/28/2005
Reviewed By: Kevin Sheth, M.D., Department of Neurology, Brigham and Women's Hospital and Massachusetts General Hospital, Harvard Medical School, Boston, MA. Review provided by VeriMed Healthcare Network.

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. Copyright 2004 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.