To aid in the diagnosis of narcolepsy, which test is performed?

The multiple sleep latency test (MSLT) is a crucial tool in diagnosing narcolepsy. This test measures how quickly a person falls asleep in a quiet environment during the day, and it assesses the degree of daytime sleepiness. In the MSLT, a patient typically takes a series of naps at two-hour intervals throughout the day.

For individuals with narcolepsy, the test often reveals a significantly shortened latency to sleep onset and frequent episodes of REM sleep occurring during these daytime naps. This is distinctive and helps differentiate narcolepsy from other sleep disorders characterized by excessive daytime sleepiness.

The other tests mentioned are not specific diagnostic tools for narcolepsy. A pneumogram primarily evaluates respiratory function during sleep, the glucose tolerance test assesses blood sugar levels and is often used in diabetes screening, and a prolonged EEG generally looks for electrical activity in the brain but does not evaluate sleep architecture specific to narcolepsy. Thus, the MSLT stands out as the definitive test for confirming narcolepsy.