What are the conclusions of the Multiple Sleep Latency Test (MSLT)

From the Guidelines

The Multiple Sleep Latency Test (MSLT) should be preceded by actigraphy for 7-14 days to monitor total sleep time and establish habitual sleep-wake timing in adult and pediatric patients with suspected central disorders of hypersomnolence, as recommended by the American Academy of Sleep Medicine 1. This approach is based on the conditional recommendation that actigraphy can provide objective data on total sleep time prior to the MSLT, which is essential for accurate diagnosis and treatment of sleep disorders 1. The use of actigraphy can help identify patients with insufficient sleep syndrome and circadian rhythm sleep-wake disorders, which may impact the interpretation of the MSLT results 1. Key points to consider when interpreting MSLT results include:

• A mean sleep latency greater than 10 minutes with no sleep-onset REM periods (SOREMPs) is considered normal
• A mean sleep latency of 8 minutes or less, plus two or more SOREMPs, is indicative of narcolepsy
• A mean sleep latency of 8 minutes or less with fewer than two SOREMPs suggests idiopathic hypersomnia Treatment of sleep disorders diagnosed using the MSLT may involve wake-promoting medications, stimulants, and lifestyle modifications, such as maintaining regular sleep schedules and avoiding alcohol and sedating medications 1.

From the FDA Drug Label

The MSLT, an objective polysomnographic assessment of the patient’s ability to fall asleep in an unstimulating environment, measured latency (in minutes) to sleep onset averaged over 4 test sessions at 2-hour intervals. For each test session, the subject was told to lie quietly and attempt to sleep Each test session was terminated after 20 minutes if no sleep occurred or 15 minutes after sleep onset.

The MSLT-1 conclusions are not directly provided in the drug label. However, the label describes the Multiple Sleep Latency Test (MSLT) as an objective measure to assess a patient's ability to fall asleep.

• The test consists of 4 sessions at 2-hour intervals, where the subject is asked to lie quietly and attempt to sleep.
• Each session is terminated after 20 minutes if no sleep occurs or 15 minutes after sleep onset.
• The test measures latency to sleep onset, which is the time it takes for the subject to fall asleep. The label does not provide specific conclusions about the MSLT-1, but it does mention that patients were required to have objectively documented excessive daytime sleepiness via an MSLT with two or more sleep onset REM periods 2.

From the Research

MSLT-1 Conclusions

• The Multiple Sleep Latency Test (MSLT) is a direct, objective method of measuring daytime sleepiness 3.
• The MSLT is used to diagnose narcolepsy, a chronic hypersomnia characterized by excessive daytime sleepiness (EDS) and manifestations of disrupted rapid eye movement sleep stage 4, 5.
• The test measures the time it takes for a person to fall asleep during the day, and the results can help differentiate between central nervous system (CNS) hypersomnias, such as narcolepsy and idiopathic hypersomnia 6.
• Sleep onset criteria at the MSLT can be used as an additional marker to differentiate CNS hypersomnias, with idiopathic hypersomnia patients showing significantly longer sustained sleep latency than sleep latency 6.
• The administration of sodium oxybate can improve MSLT sleep latency in patients with narcolepsy with cataplexy, and can also have immediate effects on polysomnographic night-time recordings, including an increase in slow wave sleep and a decrease in stage shifts and awakenings 7.
• The MSLT is a useful tool in the diagnosis and management of narcolepsy, and can be used in conjunction with other tests, such as polysomnography, to confirm the diagnosis and monitor treatment response 4, 5.