Sleep disorders testing uses polysomnography (PSG) — a comprehensive recording of the biophysiological changes that occur during sleep. PSG monitors many body functions, including brain activity (electroencephalography), eye movements (electrooculography), muscle activity or skeletal muscle activation (electromyography), and heart rhythm (echocardiography). Sleep studies are usually performed at night, when most people sleep, although some people with circadian rhythm sleep disorders may be tested at other times of day. A polysomnogram records a minimum of 12 channels requiring at least 22 wire attachments to the patient, which converge into a central unit connected to a computer system for displaying, recording, and storing the data. The channels vary depending on the physician’s request. During sleep, multiple channels can be displayed continuously and a small infrared video camera can be positioned in the room so that the technician can observe the patient on a monitor from an adjacent control room.
This article is an update of a previous post.