A polysomnogram (PSG) test is a common and painless procedure performed during an overnight sleep study. Its purpose is to evaluate your various sleep stages (sleep architecture) and monitor specific body parameters including:
- brain wave activity through an electroencephalogram (EEG)
- heart rate activity through an electrocardiogram
- body movement through an electromyogram
- eye movement through an electroculogram
- muscle tone
- breathing activity
- blood oxygen level
Why is a PSG conducted?
A PSG is typically conducted to evaluate the cause of excessive daytime sleepiness and insomnia or when another sleep disorder, such as sleep apnea or narcolepsy, is suspected.
How is a PSG performed?
Approximately two hours before bedtime a sleep technologist places electrodes on your head and body. Each one is installed using a special jelly and checked with a meter for appropriate functioning. An elastic band around the waist and heat-sensitive wires in the nose and mouth are positioned to monitor your breathing. A probe in a finger is installed to measure the level of your blood oxygen. Your bedroom is in direct contact through an intercom system with the diagnostic unit system where the sleep technologist monitors your recording overnight. Once the testing is finished, electrodes are removed and you may resume your daily activity. Your sleep disorders physician will shortly after interpret your polysomnograph test and inform you and your referring physician about the results.
