• Alternative Names

    Daytime sleep disorder; Cataplexy


    The most common symptoms of narcolepsy are:

    • Periods of extreme drowsiness every 3 to 4 hours during the day. You may feel a strong urge to sleep, often followed by a short nap (sleep attack).
      • These periods last for about 15 minutes each, although they can be longer.
      • They often happen after eating, but may occur while driving, talking to someone, or during other situations.
      • You wake up feeling refreshed.
    • Dream-like hallucinations may occur during the stage between sleep and wakefulness. They involve seeing or hearing, and possibly other senses.
    • Sleep paralysis is when you are unable to move when you first wake up. It may also happen when you first become drowsy.
    • Cataplexy is a sudden loss of muscle tone while awake, resulting in the inability to move. Strong emotions, such as laughter or anger, will often bring on cataplexy.
      • Most attacks last for less than 30 seconds and can be missed.
      • Your head will suddenly fall forward, your jaw will become slack, and your knees will buckle.
      • In severe cases, a person may fall and stay paralyzed for as long as several minutes.

    Not all patients have all four symptoms.

    Signs and tests

    The doctor will perform a physical exam and order blood work to rule out conditions that can cause similar symptoms. Conditions that can cause excessive sleepiness include:

    • Insomnia and other sleep disorders
    • Restless leg syndrome
    • Seizures
    • Sleep apnea
    • Other medical, psychiatric, or nervous system diseases

    Other tests may include:

    • ECG (measures the heart's electrical activity)
    • EEG (brain activity measurements)
    • Monitoring of breathing
    • Genetic testing to look for narcolepsy gene

    Tests will also include a sleep study (polysomnogram). The Multiple Sleep Latency Test (MSLT) may be used to help diagnose narcolepsy. This test measures how long it takes you to fall asleep during a daytime nap. Patients with narcolepsy fall asleep much faster than people without the condition.