University of Iowa Department of Neurology
First Published: 2000
Last Revised: October 2003
Peer Review Status: Internally Peer Reviewed
What is a sleep study?
A sleep study or polysomnogram (PSG) is a test that examines a person's sleeping behavior. It is an all-night procedure where a professional PSG technologist applies several electrodes to your scalp, chin, chest and legs to monitor your brain waves, heart activity and body movements during sleep. An elastic belt is placed around your abdomen in order to record respirations. Two thin wires are placed near your nose and mouth to record air flow during breathing. Finally, a small device is placed on your finger to measure your oxygen level. The entire sleep study procedure is painless.
The technologist monitors the recordings in another room. You will be in a private room with an intercom so that you may call the technologist at any time during the sleep study.
After testing is completed in the morning, the technologist will disconnect all of the electrodes and clean your skin, at which time your testing is complete and you may return home. The results of your sleep study will be sent to your referring physician.
Why is a sleep study performed?
A sleep study, or PSG, is performed to help evaluate sleeping disorders, which typically are:
A condition that causes a person to stop breathing during sleep on occasions throughout the night. Symptoms include daytime sleepiness, loud snoring or frequent awakenings during the night.
A condition that causes a person to fall asleep suddenly at inappropriate times, such as while talking, eating or driving. There may be a sudden loss of muscle strength (cataplexy), which may cause the person to stumble or fall, usually during emotional times, such as when laughing or crying.
A condition in which a person has difficulty falling or staying asleep. This disorder may be caused by various problems such as tension, medications, or apnea.
With this condition, sleep may be disturbed by spontaneous twitches or jerks in the limbs.
The sleep study is analyzed by technologists and physicians specifically trained in sleep disorders. The results assist your physician in diagnosing a sleep problem.
We realize that your sleep in the test situation may not be truly representative of your sleep at home; however, the information gained is still very useful. Most sleep disorders can be effectively treated once they have been diagnosed.