Another creation for the Somnus Sleep Clinic Website:
A polysomnogram (also know as a PSG) is an overnight sleep study. A PSG is useful in the diagnosis of several sleep disorders, especially obstructive sleep apnea.
Before the test begins, our technicians spend about 45 minutes applying the painless electrodes, sensors, and monitors to the patient.
EEG Electrodes on the scalp are used to monitor brainwaves. Electrodes are also applied to the chin to measure muscle tone and next to the eyes to monitor eye movements. These 3 sets of electrodes are used to determine stage and depth of sleep.
Electrodes are attached to the lower legs to monitor for the leg movements that characterize the disease Periodic Limb Movement Disorder.
To monitor breathing, airflow monitors are placed at the mouth and nose. The monitor at the nose is similar to an oxygen cannula. Belts are placed across the chest and abdomen to detect respiratory effort. These belts are useful in distinguishing between the 2 types of sleep apnea. An oximeter is placed on one finger to detect decreases in oxygen, which are common in obstructive sleep apnea.
Several electrodes are applied to the chest to monitor heart rate and rhythm.
Many patients ask if is possible to get up in the middle of the night during a PSG. It takes a technician only about a minute to help the patient wrap the wires around his neck and get out of bed. Then the patient can easily walk around
A PSG lasts about 8 hours. After the procedure is finished, it takes about 10 minutes to remove the electrodes and sensors. A shower with plenty of shampoo is necessary to remove the electrode gel from the hair!