Laboratory Sleep Test

What is a Polysomnogram (PSG)?

A Polysomnogram (also known as an overnight sleep study, laboratory sleep test, or a PSG) is used to diagnose many sleep disorders ranging from sleep apnea to restless leg syndrome to narcolepsy.

The test measures many "channels" including:

• Heart rate
• Brain waves
• Blood oxygen levels
• Breathing rate
• Muscle activity
• Eye movement
• Body position
• Sleep cycles

Why would I ever need a PSG?

The reason why you would participate in an overnight sleep study is that your doctor may suspect that you have a sleeping disorder. The test will determine whether you have a sleep disorder and what it might be.

A sleep study can confirm a diagnosis of:

• Obstructive sleep apnea (OSA)
• Narcolepsy
• Fatigue or excessive daytime sleepiness
• Insomnia
• Restless leg syndrome
• Issues with circadian rhythms (falling asleep or waking at inappropriate times)
• REM behavior disorder (physically acting out dreams)

What happens during the test?

The sleep study will take place in a laboratory, where technicians will monitor how you sleep throughout the night. You will be asked to arrive two hours before bedtime so the technician can prepare you for the test. Several sensors, or electrodes, will be placed on your body to monitor your activity while you sleep. You will sleep in a room, similar to a hotel room, while a technician monitors your progress in a separate room.

The technician will record the time it takes you to fall asleep, as well as how often you wake during the night. He or she will take note of the number of times you stop breathing or nearly stop breathing throughout the night. At some sleep centers, a video camera records your body movements throughout the night.

Different types of sleep studies:

Your doctor may ask you participate in an additional sleep study for a more comprehensive sleep evaluation. Some other types of sleep studies include:

 Nap study or Multiple sleep latency test (MSLT)

Nap studies are follow-up studies that help healthcare providers accurately assess the type of sleep disorder you have and possible lines of treatment.

A nap study begins the morning after an overnight study. During the study, you will be asked to have short naps throughout the day. In this study, a technician will monitor the length and quality of your sleep during your nap, as well as your breathing and heart rate.

Maintenance wakefulness test (MWT)

A maintenance wakefulness test measures how alert you are during the day, and how long you are able to stay awake for a specific period of time.

Two night PSG with CPAP titration

Your healthcare provider may order a two-night sleep study if he or she suspects you may have sleep apnea. If the results from the overnight evaluation show that you have sleep apnea, you will be asked to spend an additional night at the lab so the technician can determine the right amount of pressure for your CPAP machine.

Split night PSG with CPAP titration

If your doctor suspects you have moderate to severe sleep apnea, you will be monitored during the first half of the night, and the second half of the night is spent determining the right amount of pressure for your CPAP machine.

Home Sleep Test (HST)

The Home Sleep Test is becoming increasingly popular, because the study is conducted in the comfort and privacy of your own home. These tests are performed on state-of-the-art equipment and there are no technicians or sensors monitoring your every move. Instead, you will fall asleep as you normally do wearing a device that will record your breathing, heart rate and REM movement. The data is collected overnight and turned into your doctor. Home tests are less expensive and less invasive than a traditional lab study. However, it is possible that a sleep disorder may need further diagnosis with a sleep study in a laboratory.

What happens after the test?

Once you’ve completed the overnight sleep study, the data collected from your study will be analyzed so a proper diagnosis can be made. A typical sleep study consists of 1000 pages of data, and may take some time to process the results. Your doctor will give you feedback from the study once the data has been processed, and discuss the results and possible treatment options.

What are my options for treatment?

Depending on what type of sleep disorder you have, your doctor may prescribe several different treatments – ranging from lifestyle changes to PAP therapy.

Treatment options include:

• Positive Airway Pressure (PAP) therapy
• Surgery
• Oral appliances

Generally speaking, if you have mild to moderate sleep apnea, the best course of treatment involves simple lifestyle changes and sleeping with an oral device. In moderate to severe cases, PAP therapy is used. Surgery is usually the last resort in the line of treatment in the most severe cases.

 For more Frequently Asked Questions about Sleep Testing, Click Here.