Which type of sleep study is most appropriate for assessing a suspected case of narcolepsy?

The Multiple Sleep Latency Test (MSLT) is particularly suited for assessing suspected cases of narcolepsy because it measures the speed of falling asleep during the day. This test typically follows a nighttime polysomnography study and is specifically designed to evaluate excessive daytime sleepiness, a hallmark symptom of narcolepsy. During the MSLT, the patient is given several opportunities throughout the day to nap in a sleep lab setting, and the time it takes them to fall asleep is recorded. A significantly short sleep latency (usually less than 8 minutes) or the occurrence of REM sleep within these naps can indicate narcolepsy.

Polysomnography is vital for diagnosing sleep disorders in general, including narcolepsy, by providing a record of sleep stages and breathing patterns, but it alone does not focus specifically on the daytime sleepiness aspect that is central to narcolepsy. Home sleep apnea testing is primarily used to evaluate obstructive sleep apnea and would not adequately address the symptoms and characteristics of narcolepsy. Actigraphy tracks sleep patterns based solely on movement and does not provide detailed information about the stages of sleep or the presence of REM sleep, which are critical for a narcolepsy diagnosis. Thus, the MSLT is the most effective tool