A Multiple Sleep Latency Test (MSLT) test measures the propensity to fall asleep during quiet situations. It objectively evaluates daytime sleepiness by measuring the time to sleep onset during naps scheduled at equal intervals throughout the day under standardized conditions.
The MSLT is a non-invasive, painless procedure during which electrodes are placed to monitor the brain, heart, muscles and eye activity as well as airflow and blood oxygen levels during the various sleep stages. A MSLT test is commonly used to confirm or rule out narcolepsy.
Narcolepsy is confirmed when the average sleep onset latency is less than 8 minutes and when the patient has at least two naps associated with a REM (dream) period.