How is narcolepsy diagnosed?

Narcolepsy is diagnosed after your healthcare provider performs a detailed medical and sleep history, physical examination, medication history and sleep studies (which are performed in a sleep disorders center). You may also be asked to wear a wrist motion sensor (called an actigraph) for a few weeks or keep a sleep diary, which consists of keeping notes about how easy it is for you to fall asleep and stay asleep, how many hours of sleep you get each night and how awake you feel during the day.

Two essential sleep studies to confirm a diagnosis of narcolepsy are the polysomnogram (PSG) and the multiple sleep latency test (MSLT). These tests are usually performed in a sleep disorders center and require an overnight stay.

  • The PSG is an overnight test that takes continuous multiple measurements, including heart rate, oxygen level, breathing rate, eye and leg movements and brain waves while you sleep. A PSG reveals how quickly you fall asleep, how often you wake up during the night and how often REM sleep is disturbed (a common finding in people with narcolepsy). This study also helps determine if your symptoms are caused by another condition, such as obstructive sleep apnea. Most people with narcolepsy show disruptions in normal sleep patterns, with frequent awakenings.
  • The MSLT is performed during the daytime, the day after the PSG test. During MSLT, you will take five short naps, scheduled two hours apart. The MSLT measures how quickly you fall asleep and how quickly you enter into REM sleep.

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