Polysomnogram (overnight study)

A polysomnogram measures abnormalities in the sleep cycle. It is done overnight. Electrodes placed on the skin and scalp are connected to recording equipment to monitor and record the following body functions during sleep: airflow and respiratory effort, sound, blood oxygen levels, heart rate, electrical activity in the brain, eye movement and muscle movement.

CPAP Titration (overnight study)

A continuous positive airway pressure (CPAP) titration study is an overnight study to set the correct air pressure for treatment. When you come in you are fitted for a CPAP mask and then hooked up to the polysomnography equipment. During the night the pressure of the air coming from the CPAP machine is gradually increased until your breathing is normalized and your correct CPAP pressure has been determined.

Animation provided courtesy of NHLBI.

Multiple Sleep Latency Test (daytime study)

A multiple sleep latency test (MSLT) is conducted, along with a polysomnogram, to confirm or rule out narcolepsy. It is a daytime test that monitors a series of naps to uncover if a person has daytime sleepiness, the severity of it and the inappropriate presence of early onset REM sleep.

The test is usually done immediately after an overnight study. A series of five naps is taken at two-hour intervals.