This test is usually conducted in a sleep study center. The patient sleeps at the center, and the following parameters are monitored:

* Electrical activity of the brain (electroencephalogram)

* Electrical activity of the heart (electrocardiogram)

* Movements of the muscles (electromyogram)

* Eye movements (electrooculogram)

These parameters are monitored as the person passes through the various sleep stages. Characteristic patterns from the electrodes are recorded while the person is awake with eyes closed and during sleep. Continuous audiovisual recording monitors physical activity during sleep.