1. Narcolepsy is a disorder that causes periods of extreme daytime sleepiness. Rarely, people who have this disorder fall asleep suddenly during routine activities. Most people who have narcolepsy also have trouble sleeping at night.

2. Narcolepsy also may cause cataplexy, hallucinations (vivid dreams) during sleep, and sleep paralysis. Sleep paralysis is a condition that prevents you from moving or speaking while waking up and sometimes while falling asleep. Cataplexy is a condition that causes sudden loss of muscle tone while you're awake.

3. People who have narcolepsy have low levels of hypocretin. This is a chemical in the brain that helps control levels of wakefulness. Researchers think that certain factors may work together to cause a lack of hypocretin. Examples of these factors include heredity; brain injuries; contact with toxins, such as pesticides; and autoimmune disorders.

4. Narcolepsy affects between 50,000 and 2.4 million people in the United States. Symptoms usually begin during the teen or young adult years. Narcolepsy affects both men and women.

5. The four major signs and symptoms of narcolepsy are extreme daytime sleepiness, cataplexy (muscle weakness) while awake, and hallucinations and sleep paralysis during sleep. Most people who have narcolepsy also don't sleep well at night. They may have trouble falling and staying asleep. Vivid, scary dreams may disturb sleep.

6. It can take as long as 10 to 15 years after the first symptoms appear before narcolepsy is recognized and diagnosed. This is because narcolepsy is fairly rare. Also, many of the symptoms of narcolepsy are liked symptoms of other illnesses.

7.Narcolepsy is diagnosed based on your signs and symptoms, your medical and family histories, a physical exam, and results from tests.

8. Narcolepsy has no cure. However, medicines, lifestyle changes, and other therapies can relieve many of its symptoms. Treatment for narcolepsy is based on the type of symptoms you have and how severe they are.

9. Living with narcolepsy can be hard. It can affect your ability to drive, work, go to school, and have relationships. Besides taking medicine, you can do many things to live a safe and satisfying life. Talk to your doctor about how to cope with your condition.