Narcolepsy (NAR-ko-lep-se) is a disorder that causes periods of extreme daytime sleepiness. The disorder also may cause muscle weakness.
Most people who have narcolepsy have trouble sleeping at night. Some people who have the disorder fall asleep suddenly, even if they're in the middle of talking, eating, or another activity.
Narcolepsy also can cause:
The two main phases of sleep are nonrapid eye movement (NREM) and rapid eye movement (REM). Most people are in the NREM phase when they first fall asleep. After about 90 minutes of sleep, most people go from NREM to REM sleep.
Dreaming occurs during the REM phase of sleep. During REM, your muscles normally become limp. This prevents you from acting out your dreams. (For more information about sleep cycles, go to the National Heart, Lung, and Blood Institute's "Your Guide to Healthy Sleep.")
People who have narcolepsy often fall into REM sleep quickly and wake up directly from it. As a result, they may have vivid dreams while falling asleep and waking up.
Hypocretin (hi-po-KREET-in), a chemical in the brain, helps promote wakefulness. Most people who have narcolepsy have low levels of this chemical. What causes these low levels isn't well understood.
Researchers think that certain factors may work together to cause a lack of hypocretin. These factors may include heredity, infections, brain injuries, and autoimmune disorders. (Autoimmune disorders occur if the body's immune system mistakenly attacks the body's cells and tissues.)
Narcolepsy symptoms usually begin during the teen or young adult years. People who have narcolepsy may find it hard to function at school, work, home, and in social situations because of extreme tiredness.
Narcolepsy has no cure, but medicines, lifestyle changes, and other therapies can improve symptoms. Research is ongoing on the causes of narcolepsy and new ways to treat it.
Most people who have narcolepsy have low levels of hypocretin. This is a chemical in the brain that helps promote wakefulness. What causes low hypocretin levels isn't well understood.
Researchers think that certain factors may work together to cause a lack of hypocretin. These factors may include:
Some research suggests that environmental toxins may play a role in triggering narcolepsy. Toxins may include heavy metals, pesticides and weed killers, and secondhand smoke.
Heredity alone doesn't cause narcolepsy. You also must have at least one other factor, such as one of those listed above, to develop narcolepsy.
Narcolepsy affects men and women. Symptoms usually begin during the teen or young adult years. The disorder also can develop later in life or in children, but it's rare before age 5.
Researchers think that certain factors may work together to cause narcolepsy. If these factors affect you, you may be at higher risk for the disorder. (For more information, go to "What Causes Narcolepsy?")
The four major signs and symptoms of narcolepsy are extreme daytime sleepiness, cataplexy (muscle weakness) while awake, and hallucinations and sleep paralysis during sleep.
If you have narcolepsy, you may have one or more of these symptoms. They can range from mild to severe. Less than one-third of people who have narcolepsy have all four symptoms.
All people who have narcolepsy have extreme daytime sleepiness. This often is the most obvious symptom of the disorder.
During the day, you may have few or many periods of sleepiness. Each period usually lasts 30 minutes or less. Strong emotions—such as anger, fear, laughter, or excitement—can trigger this sleepiness.
People who have daytime sleepiness often complain of:
Some people who have narcolepsy have episodes in which they fall asleep suddenly. This is more likely to happen when they're not active—for example, while reading, watching TV, or sitting in a meeting.
However, sleep episodes also may occur in the middle of talking, eating, or another activity. Cataplexy also may occur at the same time.
This condition causes loss of muscle tone while you're awake. Muscle weakness affects part or all of your body.
Cataplexy may make your head nod or make it hard for you to speak. Muscle weakness also may make your knees weak or cause you to drop things you're holding. Some people lose all muscle control and fall.
Strong emotions—such as anger, surprise, fear, or laughter—often trigger cataplexy. It usually lasts a few seconds or minutes. During this time, you're usually awake.
Cataplexy may occur weeks to years after you first start to have extreme daytime sleepiness.
If you have narcolepsy, you may have vivid dreams while falling asleep, waking up, or dozing. These dreams can feel very real. You may feel like you can see, hear, smell, and taste things.
This condition prevents you from moving or speaking while falling asleep or waking up. However, you're fully conscious (aware) during this time. Sleep paralysis usually lasts just a few seconds or minutes, but it can be scary.
Most people who have narcolepsy don't sleep well at night. They may have trouble falling and staying asleep. Vivid, scary dreams may disturb sleep. Not sleeping well at night worsens daytime sleepiness.
Rarely, people who fall asleep in the middle of an activity, such as eating, may continue that activity for a few seconds or minutes. This is called automatic behavior.
During automatic behavior, you're not aware of your actions, so you don't do them well. For example, if you're writing before falling asleep, you may scribble rather than form words. If you're driving, you may get lost or have an accident. Most people who have this symptom don't remember what happened while it was going on.
Children who have narcolepsy often have trouble studying, focusing, and remembering things. Also, they may seem hyperactive. Some children who have narcolepsy speed up their activities rather than slow them down.
Children who have narcolepsy may have severe sleepiness. They may fall asleep while talking or eating, or during sporting events and social activities.
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 narcolepsy symptoms are like symptoms of other illnesses, such as infections, depression, and sleep disorders.
Narcolepsy sometimes is mistaken for learning problems, seizure disorders, or laziness, especially in school-aged children and teens. When narcolepsy symptoms are mild, the disorder is even harder to diagnose.
Your doctor will diagnose narcolepsy based on your signs and symptoms, your medical and family histories, a physical exam, and test results.
Tell your doctor about any signs and symptoms of narcolepsy that you have. This is important because your doctor may not ask about them during a routine checkup.
Your doctor will want to know when you first had signs and symptoms and whether they bother your sleep or daily routine. He or she also will want to know about your sleep habits and how you feel and act during the day.
To help answer these questions, you may want to keep a sleep diary for a few weeks. Keep a daily record of how easy it is to fall and stay asleep, how much sleep you get at night, and how alert you feel during the day.
For a sample sleep diary, go to the National Heart, Lung, and Blood Institute's "Your Guide to Healthy Sleep."
Your doctor may ask whether:
Your doctor will check you to see whether another condition is causing your symptoms. For example, infections, certain thyroid diseases, drug and alcohol use, and other medical or sleep disorders may cause symptoms similar to those of narcolepsy.
If your doctor thinks you have narcolepsy, he or she will likely suggest that you see a sleep specialist. This specialist may advise you to have sleep studies to find out more about your condition.
Sleep studies usually are done at a sleep center. Doctors use the results from two tests to diagnose narcolepsy. These tests are a polysomnogram (PSG) and a multiple sleep latency test (MSLT).
Polysomnogram. You usually stay overnight at a sleep center for a PSG. The test records brain activity, eye movements, heart rate, and blood pressure. A PSG can help find out whether you:
Multiple sleep latency test. This daytime sleep study measures how sleepy you are. It's often done the day after a PSG. During the test, you're asked to nap for 20 minutes every 2 hours throughout the day. (You will nap a total of four or five times.)
A technician checks your brain activity during this time. He or she notes how quickly you fall asleep and how long it takes you to reach various stages of sleep.
An MSLT finds out how quickly you fall asleep during the day (after a full night's sleep). It also shows whether you go into REM sleep soon after falling asleep.
Hypocretin test. This test measures the level of hypocretin in the fluid that surrounds your spinal cord. Most people who have narcolepsy have low levels of hypocretin. Hypocretin is a chemical that helps promote wakefulness.
To get a sample of spinal cord fluid, a spinal tap (also called a lumbar puncture) is done. For this procedure, your doctor inserts a needle into your lower back area and then withdraws a sample of your spinal fluid.
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.
Not all medicines and lifestyle changes work for everyone. It may take weeks to months for you and your doctor to find the best treatment.
You may need one or more medicines to treat narcolepsy symptoms. These may include:
Some prescription and over-the-counter medicines can interfere with your sleep. Ask your doctor about these medicines and how to avoid them, if possible. For example, your doctor may advise you to avoid antihistamines. These medicines suppress the action of histamine, a substance in the blood that promotes wakefulness.
If you take regular naps when you feel sleepy, you may need less medicine to stay awake.
Lifestyle changes also may help relieve some narcolepsy symptoms. You can take steps to make it easier to fall asleep at night and stay asleep.
Certain activities, foods, and drinks before bedtime can keep you awake. Try to follow these guidelines:
For more tips on sleeping better, go to the National Heart, Lung, and Blood Institute's "Your Guide to Healthy Sleep."
Light therapy may help you keep a regular sleep and wake schedule. For this
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 fulfilling life.
Driving can be dangerous for people who have narcolepsy. Ask your doctor whether you can drive safely. To help make it safer for you to drive:
People who have narcolepsy can work in almost any type of job, but some jobs may be better than others.
For example, a job with a flexible work schedule can make it easier to take naps when needed. A job in which you interact with your coworkers can help keep you awake. Jobs that don't require you to drive or are closer to home also may better suit your needs.
Certain laws may apply to workers who have medical conditions, such as narcolepsy. These laws include the:
Living with narcolepsy may cause fear, anxiety, depression, and stress. Talk about how you feel with your health care team. Talking to a professional counselor also can help. If you're very depressed, your doctor may recommend medicines or other treatments that can improve your quality of life.
Joining a patient support group may help you adjust to living with narcolepsy. You can see how other people who have the same symptoms have coped with them. Talk with your doctor about local support groups or check with an area medical center.
Support from family and friends also can help relieve stress and anxiety. Let your loved ones know how you feel and what they can do to help you.
Children who have narcolepsy may have trouble studying, focusing, and remembering things. To help your child in school:
If you're pregnant or planning a pregnancy, ask your doctor whether you should continue taking your narcolepsy medicines. Certain medicines may interfere with your pregnancy.
The National Heart, Lung, and Blood Institute (NHLBI) is strongly committed to supporting research aimed at preventing and treating heart, lung, and blood diseases and conditions and sleep disorders.
NHLBI-supported research has led to many advances in medical knowledge and care. Often, these advances depend on the willingness of volunteers to take part in clinical trials.
Clinical trials test new ways to prevent, diagnose, or treat various diseases and conditions. For example, new treatments for a disease or condition (such as medicines, medical devices, surgeries, or procedures) are tested in volunteers who have the illness. Testing shows whether a treatment is safe and effective in humans before it is made available for widespread use.
By taking part in a clinical trial, you can gain access to new treatments before they're widely available. You also will have the support of a team of health care providers, who will likely monitor your health closely. Even if you don't directly benefit from the results of a clinical trial, the information gathered can help others and add to scientific knowledge.
If you volunteer for a clinical trial, the research will be explained to you in detail. You'll learn about treatments and tests you may receive, and the benefits and risks they may pose. You'll also be given a chance to ask questions about the research. This process is called informed consent.
If you agree to take part in the trial, you'll be asked to sign an informed consent form. This form is not a contract. You have the right to withdraw from a study at any time, for any reason. Also, you have the right to learn about new risks or findings that emerge during the trial.
For more information about clinical trials related to narcolepsy, talk with your doctor. You also can visit the following Web sites to learn more about clinical research and to search for clinical trials:
For more information about clinical trials for children, visit the NHLBI's Children and Clinical Studies Web page.
The NHLBI updates Health Topics articles on a biennial cycle based on a thorough review of research findings and new literature. The articles also are updated as needed if important new research is published. The date on each Health Topics article reflects when the content was originally posted or last revised.