Sleep Apnea Tests and Diagnosis

Medically Reviewed by Nayana Ambardekar, MD on March 19, 2024
3 min read

If you have symptoms of sleep apnea, your doctor may ask you to have a sleep apnea test, called a polysomnogram (PSG). This may be done in a sleep disorder center or even at home.

A polysomnogram -- or sleep study -- is a multiple-component test that electronically sends and records specific physical activities while you sleep. The recordings are analyzed by a qualified sleep specialist to find out if you have sleep apnea or another type of sleep disorder.

If the test shows sleep apnea, you may need more sleep testing to figure out the best treatment option.

Your doctor will tell you whether to take your medications as usual or stop using them before the test. Don’t have any caffeine or alcohol the day of the test, because they can interfere with the results. Bring comfortable pajamas, a book or magazine, and a special pillow if you use one.

On the night of your sleep study, if you’re in a sleep center lab, you’ll be assigned to a private bedroom in the sleep center or hospital. Near the bedroom will be a central monitoring area, where the technicians monitor sleeping patients. You’ll have a private bathroom; just let the technicians know when you need to use it so they can take off the wires connecting you to the monitoring equipment.

You’ll be hooked up to equipment that may look uncomfortable. But most people fall asleep with little trouble.

Similar, more portable equipment is available for home testing, especially for less complicated cases or situations.

During a sleep study, surface electrodes will be put on your face and scalp and will send recorded electrical signals to the measuring equipment. These signals, which are generated by your brain and muscle activity, are recorded digitally. Belts around your chest and abdomen measure your breathing. A bandage-like oximeter probe on your finger measures the oxygen in your blood.


  • EEG (electroencephalogram) to measure and record brain wave activity
  • EMG (electromyogram) to record muscle activity such as face twitches, teeth grinding, and leg movements, and to look for REM stage sleep. During REM sleep, intense dreams often happen as the brain has heightened activity.
  • EOG (electrooculogram) to record eye movements. These movements are important in determining the different sleep stages, particularly REM stage sleep.
  • EKG (electrocardiogram) to record heart rate and rhythm
  • Nasal airflow sensor to record airflow
  • Snore microphone to record snoring activity


In the morning, the technicians take off the sensors attached to your skin, and you go back to your everyday activities.

It takes the sleep specialist some time to go over the hundreds of pages of data from the study. They’ll send the results to your doctor. Once your doctor reviews them, you’ll meet to talk about the findings and next steps.

The data will include information about your sleep, such as:

  • How long you spend in each sleep stage
  • How often you wake up
  • Whether you stop breathing or have trouble breathing
  • Whether you snore
  • Body position
  • Limb movements
  • Unusual brain activity patterns