How is narcolepsy diagnosed?

A doctor will perform a combination of tests to help determine if you have narcolepsy:
  • In-lab overnight sleep study (polysomnogram): A sleep study requires you to stay overnight at a sleep center so a doctor can observe and measure your sleep. Sensors attached to different parts of your body record your brain waves, heartbeat and other things while you sleep. This test will show if other health conditions, such as sleep apnea, are causing your excessive daytime sleepiness or sleep attacks.
  • Multiple Sleep Latency Test (MSLT): Also known as a nap study, the MSLT measures daytime sleepiness. The test requires you to attempt to take multiple naps at a sleep lab at set times throughout the day. It is used to see how quickly you fall asleep in quiet daytime situations. For each nap trial you are asked to lie quietly in bed in a dark room and try to go to sleep. Most people with narcolepsy fall asleep in an average of three minutes during the MSLT.
  • Hypocretin level measurement: Rarely, the doctor will measure your hypocretin (orexin) levels. Hypocretin is a brain chemical that controls arousal, wakefulness and appetite. People with narcolepsy with cataplexy usually have a lack of hypocretin. Because this exam requires a lumbar puncture (spinal tap) it is rarely used.

Narcolepsy cannot be diagnosed from symptoms alone, as many other sleep disorders can cause the same symptoms. Therefore, you will most likely be tested at a sleep center. During a sleep study, you stay in a sleep lab. As you sleep, your brain, heart, lungs, and muscles will be monitored. A doctor will evaluate the test results. Your doctor may also recommend a spinal tap to measure your level of hypocretin, a brain chemical that helps control sleep.

Dr. Mehmet Oz, MD
Cardiology (Cardiovascular Disease)
Before you go to the doctor to discuss your narcolepsy symptoms, write down every time you experience a symptom for at least one week, and bring this journal with you.

If your doctor suspects narcolepsy, ask about the two main sleep tests that will help get you an accurate diagnosis:

1. Sleep Study or Polysomnogram: Measures your oxygen, brain waves, eye movement and other biological vitals while you sleep.

2. Multiple Sleep Latency Test: Measures how long it takes you to fall asleep during the day.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.