Polysomnogram (PSG)

What is a polysomnogram?

A polysomnogram, or PSG, is a procedure that measures important bodily functions during sleep. Many sensors are used to make these measurements. None of the sensors cause significant discomfort.

The bodily functions that are measured are:

  • Sleep -  Electrodes stuck to the scalp, ear, chin and legs tell us when you're asleep and whether you're in REM or NREM sleep (see glossary for definitions of REM and NREM.)
  • Breathing - A sensor is placed below your nose that measures airflow; elastic bands are placed around your chest and abdomen to sense when you're making breathing efforts.
  • Oxygen level - A finger clip measures the amount of oxygen in your blood.
  • Snoring - A small microphone records snoring sounds.
  • Movements - A video camera that can record images in the dark (using infrared technology) records your movements while in bed.
  • Heart rate and rhythm - Electrodes on your chest record your heartbeat (EKG). Typically you come to the sleep lab several hours before bedtime.

How can I sleep with all these things on me?

First of all, remember that none of the monitoring devices cause significant discomfort. Although we don't expect people to sleep quite as well in the center as at home, most people sleep surprisingly well. Certainly most people sleep well enough for the study to be very useful. You are free to sleep in any position you wish and may use the bathroom whenever you need. A sleep technologist is present in the adjoining control room at all times and is available to answer questions or try to make you comfortable. Each sleeping room has a television, bedside table, closet and reading light. 

How do I prepare for a PSG?

Preparation for the study is very simple; written instructions are provided to you before you have the study. 

Learn more on What To Expect.

What happens after the polysomnogram?

On the morning following your test, a preliminary report is sent to the doctor who ordered the test. However, your doctor may decide to wait until he/she receives the final report (in about ten days) before issuing recommendations. You will also receive instructions the morning after your study from the sleep lab personnel.Technologists do not have test results after test is complete.

  1. Hair - Wash your hair prior to coming and do not put spray or oil, etc. on it. (In order to work properly electrodes must be applied to clean and dry skin.)
  2. Food - Eat a good meal prior to (PSG), but avoid food that would cause heart burn, acid indigestion. No chocolate.
  3. Drink - No alcohol or caffeinated beverages for 24 hours prior to testing because they can affect test results.
  4. Complete Sleep Diary at home for 14 days prior to testing, if possible.
  5. We will provide towels, shower and toilet facilities.
  6. Nail polish or acrylics may affect test. Please remove prior to testing.
  7. Medications
  • Bring all your medications to the center. We do not dispense medications.
  • Please do not stop any medication without first consulting your personal physician.
  • We prefer you to be off sleeping medications for at least 8 days prior to this sleep study. Please check with your doctor.