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.

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.