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Computer screen showing polysomnography graph

The all-night sleep study is frequently used by sleep physicians to evaluate adult patients when they are sleeping (we also have a pediatric sleep lab).

A sleep laboratory test is extremely valuable for diagnosing and treating many sleep disorders, including neurologic disorders, movement disorders and breathing disorders at night.

All-night sleep studies (also called polysomnography) are ordered by our sleep physicians and performed in the sleep laboratory the UM Sleep Disorders Center.

Preparing for Your Sleep Study

What to Expect During a Sleep Study

The sleep laboratory is located at the University of Maryland Medical Center Midtown Campus on 827 Linden Avenue. Patients come to the laboratory between 9 and 9:30 p.m. on the appointed day. There they meet with a sleep technologist, who will explain and perform the study. The sleeping rooms are comfortable, motel-like rooms with normal (not hospital) beds. Each room has its own attached bathroom (with shower) and a television. Parking is easy in the garage next to the hospital. If you leave before 8:30 am, it is free.

For studying the quality of sleep, electrodes are applied to the scalp, sides of the head and under the chin, chest and leg. This lets us measure brain waves, heart rate, and eye movements. A sensor is placed by the nose and mouth for measurement of airflow. Belts are placed around the rib cage and abdomen for measurement of breathing movements. A clip is placed on a finger for measurement of blood oxygen levels. Other measurements may be done as required. There are no needles and no pain. The electrodes are connected to a box by the bedside for relaying the signals to a central control room. In addition, all patients are videotaped while asleep.

In the central control room, the technologist monitors the patient's sleep and general condition. Any problems with the study may be easily dealt with. Patients may easily call the technologist if there is a problem as well.

For some patients who have sleep apnea, the effects of continuous positive airway pressure (CPAP) are evaluated. Usually these are patients who have had a previous sleep study to diagnose the condition. During the CPAP study, everything is done as for a diagnostic study. In addition, a mask is fit around the nose or around the nose and mouth. During sleep, we attempt to find a pressure level that holds the airway open and lets the patient get a good night's sleep.

Patients generally get out from the study around 6:30 to 7 am. However, if an earlier wake-up is needed, the patient just needs to let the technologist know.

Once the sleep study is completed, it is scored by a scoring technologist and sent to a sleep specialist for interpretation. This entire process takes 7-10 days. The interpretation is sent to the physician who ordered the sleep study and appropriate follow-up is arranged.

Sleep studies are generally easy to tolerate, comfortable for patients, and give the sleep physician the information he/she needs to accurately diagnose and treat the sleep disorder.