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This information was reviewed and approved by Sheila Tsai, MD (3/1/2017).

An in-laboratory sleep study, also called polysomnography, is a painless, noninvasive test that records your physical state during various stages of sleep.

It provides data that are essential in evaluating sleep and sleep-related complaints and problems, such as identifying sleep stages, body position, blood oxygen levels, breathing events, muscle tone, heart rate, eye movement, brain waves, amount of snoring and general sleep behavior. If you have sleep apnea, the study will record repeated awakenings, pauses in breathing and drops in oxygen level in the blood.

Sleep studies are performed in a sleep laboratory that is specially equipped with computerized monitoring equipment. Most sleep studies take place at night. After you change into your nightclothes, the technician will connect you to a number of electrodes that will record your brain waves and muscle movements throughout the night. A microphone will record snoring, and two belt-like straps around the chest and lower abdomen will monitor muscle movement during breathing. Despite all of the equipment, most people say their sleep is not disrupted. After the technician is certain that electrodes are recording properly, the lights will be turned off, and you can go to sleep. You will be able to talk to the technician, who will constantly monitor your test from an adjoining room. The technician will also help you if you need to use the restroom during the night.

In a sleep study for sleep apnea, you may undergo a "split-night" test, in which half of the night will be used to diagnose your sleep problem, and the other half will be used to determine the best way to treat the problem. Or, you may be asked to return for another sleep study in order to determine the best way to treat your sleep apnea. In that second study (or second half of the night), you will be treated with positive airway pressure, which blows air into the nose and/or mouth to increase air pressure enough to hold the airway open and allow you to breathe. The study is done at different air pressures to determine what level works best for you.

You will be awakened in the morning; the electrodes will be removed; and you may shower and dress. Since the electrodes are applied with water-soluble glue or tape, removal is not painful. You will be asked to complete a questionnaire concerning your sleep the previous night, and then you can go home.

Your doctor will explain the results to you and talk with you about follow-up treatment, if required.

A home sleep study may be requested to evaluate for sleep apnea. This study is performed in your own home without the presence of a sleep technologist. You may be asked to come to a sleep center to learn how to set up the recording device at home. There are fewer sensors used than with an in-laboratory study. Consequently, less information is obtained, resulting in a less accurate test that in-laboratory testing; however, this test is usually sufficient to evaluate for sleep apnea. Again, your physician will explain the results to you and talk about follow-up treatment, if recommended.


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