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Narcolepsy

Definition

Narcolepsy is a sleep disorder that causes excessive sleepiness and frequent daytime sleep attacks.

Alternative Names

Daytime sleep disorder; Cataplexy

Causes, incidence, and risk factors

Narcolepsy is a nervous system disorder, not a mental illness. Anxiety does not cause narcolepsy.

Experts believe that narcolepsy is caused by reduced amounts of a protein called hypocretin, which is made in the brain. What causes the brain to produce less of this protein is unclear.

Narcolepsy tends to run in families.

Conditions that cause insomnia, such as disrupted work schedules, can make narcolepsy worse.

Symptoms

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.

Treatment

There is no known cure for narcolepsy. The goal of treatment is to control symptoms.

Lifestyle adjustments and learning to cope with the emotional and other effects of the disorder may help you function better in work and social activities. This involves:

• Eating light or vegetarian meals during the day and avoiding heavy meals before important activities
• Scheduling a brief nap (10 to 15 minutes) after meals, if possible
• Planning naps to control daytime sleep and reduce the number of unplanned, sudden sleep attacks
• Informing teachers and supervisors about the condition so you are not punished for being "lazy" at school or work

You may need to take prescription medications. The stimulant drug modafinil (Provigil) is the first choice of treatment for narcolepsy. It is much less likely to be abused than other stimulants. The medicine also helps you stay awake. Other stimulants include dextroamphetamine (Dexedrine, DextroStat) and methylphenidate (Ritalin).

Antidepressant medications can help reduce episodes of cataplexy, sleep paralysis, and hallucinations. Antidepressants include:

• Selective serotonin reuptake inhibitors (SSRIs) such as fluoxetine, paroxetine, sertraline, and venlafaxine
• Tricyclic antidepressants such as protriptyline, clomipramine, imipramine, and desipramine

Sodium oxybate (Xyrem) is prescribed to certain patients for use at night.

If you have narcolepsy, you may have driving restrictions. Restrictions vary from state to state.

Support Groups

Expectations (prognosis)

Narcolepsy is a chronic, lifelong condition. It is not a deadly illness, but it may be dangerous if episodes occur during driving, operating machinery, or similar activities. Narcolepsy can usually be controlled with treatment. Treating other underlying sleep disorders can improve symptoms of narcolepsy.

Complications

• Injuries and accidents, if attacks occur during activities
• Impairment of functioning at work
• Impairment of social activities
• Side effects of medications used to treat the disorder

Calling your health care provider

Call your health care provider if:

• You have symptoms of narcolepsy
• Narcolepsy does not respond to treatment, or you develop other symptoms

Prevention

There is no known way to prevent narcolepsy. Treatment may reduce the number of attacks. Avoid situations that aggravate the condition if you are prone to attacks of narcolepsy.

References

Dauvilliers Y, Arnulf I, Mignot E. Narcolepsy with cataplexy. Lancet. 2007;369(9560):499-511.

Morgenthaler TI, Kapur VK, Brown T, Swick TJ, Alessi C, Aurora RN, et al. Practice parameters for the treatment of narcolepsy and other hypersomnias of central origin. Sleep. 2007;30(12):1705-1711.