Narcolepsy

Basic Facts

  • Narcolepsy is a chronic sleep disorder characterized by an excessive amount of fatigue during the daytime and, in severe cases, sudden attacks of sleep.
  • People with narcolepsy find it difficult to stay awake for long periods of time and might fall asleep when having a conversation or, most dangerously, while operating machinery.
  • Patients can suffer for years before the correct diagnosis is made. 
  • There is no cure for narcolepsy, but medications and lifestyle changes can help manage symptoms.

Narcolepsy can be associated with cataplexy, which is the loss of muscle control triggered by emotional events. Cataplexy may lead to slurred speech and buckling knees or even complete paralysis. These events are uncontrollable and activated by intense emotions such as joy, laughter, fear or anger.

The symptoms of narcolepsy most commonly begin between adolescence and 25. People with narcolepsy can fall asleep without warning. They typically sleep for a short period of time, wake feeling refreshed and then eventually fall asleep again.

Narcolepsy also is characterized by abnormal rapid eye movement (REM) sleep. The brain cycles through five phases during sleep. REM typically occurs about 90 minutes after sleep begins but, in patients with narcolepsy, REM sleep occurs almost immediately in the sleep cycle, and intermittently during the waking hours. REM sleep is associated with dreams.  

Other symptoms of narcolepsy include:

  • Halluncinations – At the onset of sleep, some patients have vivid hallucinations. For example, they might have visions that someone or something is present in the bedroom.
  • Sleep paralysis – Patients may lose the ability to move and feel paralyzed for a short period of time (seconds or minutes) when falling asleep or waking up.
  • Disturbed nighttime sleep – Many patients have trouble sleeping through the night.

Narcolepsy can be mistaken for other sleep disorders that cause daytime sleepiness such as sleep apnea or restless leg syndrome.

 

 

 

The cause of narcolepsy, which affects approximately one in 2,000 people, is unknown. However, most people with narcolepsy have low levels of the chemical hypocretin, which is a neurochemical in the brain that controls wakefulness.

Researchers believe the loss of hypocretin-producing cells in the brain could be the result of an autoimmune disease, a disorder in which the body’s immune system mistakenly attacks healthy cells as if they were foreign invaders. Type 1 diabetes and rheumatoid arthritis are commonly recognized autoimmune diseases.

Researchers also have identified a gene that is linked to narcolepsy.

 

 

 

Your doctor may make a preliminary diagnosis of narcolepsy based on your excessive daytime sleepiness and sudden loss of muscle tone (cataplexy). After an initial diagnosis, your doctor may refer you to a sleep specialist for further evaluation.

Formal diagnosis requires staying overnight at a sleep center for an in-depth sleep analysis by sleep specialists. Methods of diagnosing narcolepsy and determining its severity include:

 
  • Sleep history. Your doctor will ask you for a detailed sleep history. A part of the history involves filling out the Epworth Sleepiness Scale, which uses a series of short questions to gauge your degree of sleepiness. For instance, you indicate on a numbered scale how likely it is that you would doze off in certain situations, such as sitting down after lunch.

  • Sleep records. You may be asked to keep a detailed diary of your sleep pattern for a week or two, so your doctor can compare how your sleep pattern and alertness are related.

    Often, in addition to this sleep log, the doctor will ask you to wear an actigraph. This device has the look and feel of a wristwatch. It measures periods of activity and rest and provides an indirect measure of how and when you sleep.

  • Polysomnography. This test measures a variety of signals during sleep using electrodes placed on your scalp. For this test, you must spend a night at a medical facility. The test measures the electrical activity of your brain (electroencephalogram) and heart (electrocardiogram) and the movement of your muscles (electromyogram) and eyes (electro-oculogram). It also monitors your breathing.
  • Multiple sleep latency test. This examination measures how long it takes you to fall asleep during the day. You'll be asked to take four or five naps, each nap two hours apart. Specialists will observe your sleep patterns. People who have narcolepsy fall asleep easily and enter into rapid eye movement (REM) sleep quickly.

Narcolepsy is a chronic condition; however, the majority of patients see improvement in their daytime fatigue with stimulant agents, such as modafinil.

Cataplexy can be lessened by antidepressant drugs, which work by suppressing REM sleep.

The physician may also recommend lifestyle changes including:

  • Keeping a consistent sleep schedule,
  • Scheduling short naps throughout the day,
  • Exercising regularly, and
  • Avoiding the use of tobacco or alcohol.