Narcolepsy

Diagnosis

Understanding a patient's symptoms and excluding other causes are critical for optimal treatment. This typically involves tracking a patient's sleep-wake patterns at home and conducting an overnight study at Mayo Clinic's sleep center, followed by more testing the next day.

Tests include:

• Actigraphy: Sleep-wake cycles are tracked in the patient's home, using a small device worn like a wristwatch.
  
• Polysomnogram: Sensors applied to the skin's surface painlessly record brain wave activity, eye movements, breathing function, oxygen levels, heart rate and muscle activity during sleep. This test is used to rule out other sleep disorders that can cause excessive daytime sleepiness, such as obstructive or central sleep apnea.
  
• Multiple sleep latency test (MSLT): Patients are asked to fall asleep for a series of four or five naps, each two hours apart. People with narcolepsy fall asleep quickly and also enter rapid eye movement (REM) sleep — the dream stage of sleep — very quickly. SOREMPS (sleep onset rapid eye movement periods) are a key characteristic of narcolepsy. This test is conducted the day after a polysomnogram.
  

Because a sleep deficit and/or some medications can interfere with the above tests, patients need to ensure adequate and regular sleep two weeks prior to the tests, and may also need to stop taking certain medications.