During a sleep study the sleep cycles and stages of sleep are monitored. Electrodes are placed to monitor continuous recordings of brain waves, electrical activity of muscles, eye movement, respiratory rate, blood pressure, blood oxygen saturation, and heart rhythm. Direct observation of the person during sleep may also be used. The test is performed for people who suffer from insomnia, excessive daytime sleepiness, obstructive sleep apnea, breathing difficulties during sleep, or behavior disturbances during sleep.
Denis Hadjiliadis, MD, Assistant Professor of Medicine, Division of Pulmonary, Allergy and Critical Care, University of Pennsylvania, Philadelphia, PA. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.