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Types of Sleep Tests

Polysonography, also called a sleep study, is a test used to diagnose sleep disorders. It records brain waves (EEG), the oxygen level in the blood, heart rate and breathing, as well as eye and leg movements. The test is performed throughout the night or during the day for shift workers. Together with the sleep history, the results of the sleep study are used to diagnose over 80 sleep disorders. The most common being obstructive sleep apnea.

CPAP Titration is an all-night polysomnogram in which Continuous Positive Airway Pressure (CPAP) is used. A mask is worn over the nose or over the nose and mouth. A tube connects the mask to the CPAP machine that blows room air into the nose to keep the airway open. During the study, the airflow pressure is adjusted (titrated) to determine the correct pressure to eliminate sleep apnea episodes and snoring.

The Multiple Sleep Latency Test (MSLT) is performed during the day following an all-night polysomnogram and consists of 4-5 nap opportunities about 2 hours apart. The naps last about 20-35 minutes. The time taken to fall asleep, based on the EEG, is averaged from all naps. This provides a measure of the degree of daytime sleepiness. The occurrence of REM sleep in the naps helps to diagnosis narcolepsy.

The Maintenance of Wakefulness Test (MWT) is a daytime test that consists of four 40-minute alertness measurements in which the patient is asked to stay awake while sitting in a quiet and dimly lit room. EEG recording is used to determine if the patient falls asleep. The average time to fall asleep, if sleep occurs, is used as a measure of the ability of an individual to stay awake in non-stimulating environments. The MWT is used to evaluate fitness to return to work in high-risk occupations.