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Polysomnography (PSG)


Polysomnography is a sleep study that measures your sleep cycles and involuntary functions during sleep by recording brain waves (EEG), electrical activity of muscles, eye movement, breathing rate, blood pressure, blood oxygen saturation, and heart rhythm. This test is often referred to as the standard overnight sleep study.

A typical polysomnogram records the following data:

Dr. Streff with monitoring equipment

  • Brain waves (electrodes placed on the scalp)
  • Eye movement (electrodes placed on the face, by the eyes)
  • Chin muscle tone (electrodes placed on or under the chin)
  • Heart rate (electrodes placed on the chest)
  • Leg movements (electrodes placed on the legs)
  • Breathing (breathing sensor placed near the nose and mouth)
  • Breathing effort (two small belts placed loosely around the chest and abdomen)
  • Oxygen level (small sensor attached to the finger)
  • Audio and video taping

What to Expect
A specially trained health care provider will directly observe you on a monitor while you sleep.

You will lie on a bed in one of the sleep lab’s bedrooms. The test will be carried out under conditions similar to your normal sleep pattern. If you typically sleep at night, the test will be done at night.. 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
It is important that you do not take any sleeping medication and do not drink alcohol or caffeine-containing beverages before the test.

Why the Test Is Done
It is used to help detect a variety of sleep disorders, including:

Will I be able to sleep with all those sensors on?

Probably. Most people sleep reasonably well during sleep studies, so that we can obtain a reliable sample of the individual’s sleep pattern. The sensors are applied so that you can move in your sleep, change body positions while in bed, and use the bathroom. The sleep rooms are set up like normal, comfortable bedrooms, and our staff makes the environment as comfortable as possible. Patients can control the bedroom’s temperature themselves.

Will the Sensor Devices or Tests Hurt?

No. This is a painless and non-invasive (no needles) testing procedure

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