A polysomnogram, or sleep study, is a test that uses several types of measurements to identify sleep stages and various sleep problems. The brain controls sleep and its different stages including drowsiness, light sleep, deep sleep, and dream sleep. To determine the stage of sleep requires measuring different activities of the brain and body. These activities include brain waves (EEG), eye movements, and muscle tone. A full sleep study will measure other parameters as well, including respiratory effort (chest and abdominal wall movements), cardiac rhythm (EKG), leg movements, and oxygen saturation
Sleep studies also may be videotaped for later review of any abnormal body movements observed during the study.
We monitor the activities that occur during sleep by applying wires with small metal discs called electrodes to the head and skin. Flexible Velcro belts are placed around the chest and abdomen to measure breathing effort. The level of oxygen carried in the blood and heart rate are monitored by a clasp that fits on the index finger. None of these devices are painful and all are designed to be as comfortable as possible. At most sleep lab centers, the surroundings (especially the bedrooms) are relaxing and comfortable, like a hotel room. The technical equipment and technicians will be in a room separate from the sleeping room, and the electrode wires will be gathered together so that rolling over and changing positions will be almost as easy as it would be at home.