Multiple sleep latency test (MSLT)

The gold standard physiological evaluation in the evaluation of excessive daytime sleepiness (EDS) is the multiple sleep latency test (MSLT) (used in a specialist sleep setting)

• provides objective measurement of rapidity of sleep onset
• MSLT measures an individual’s physiologic sleep tendency when potential alerting environmental or circadian cues are controlled. One of the main advantages of this test is that the degree of sleepiness cannot be exaggerated by the patient. Sleep latency is assessed over five daytime nap trials of 20 minutes each, at two hour intervals
• mainly used for diagnosing narcolepsy or idiopathic hypersomnia
• overall mean sleep latency <10 minutes is considered clinically significant and patients with narcolepsy have a mean sleep latency <8 minutes

Reference:

• Brown J, Makker KM. An approach to excessive daytime sleepiness in adults. BMJ 2020;368:m1047