Narcolepsy
What is Narcolepsy?
Narcolepsy is a chronic central nervous system (CNS) disorder that causes patients to suddenly fall asleep, often at unexpected moments. The sleep disorder is the result of a malfunction in the brain that prevents the proper regulation of sleep-wake cycles.
Patients with narcolepsy feel drowsy much of the time and generally find it difficult to remain awake for extended periods. Though they do not sleep more often than other people do, their bodies are unable to properly control the normal boundaries between sleeping and waking. Narcolepsy can be hazardous if a patient falls asleep while driving or climbing stairs.
There are four stages of non-rapid eye movement sleep that progress from light to deep. Following these stages is rapid eye movement (REM) sleep, a stage in which a person’s muscles are temporarily paralyzed and dreaming occurs. Initially, brain waves slow down for an hour or two before brain activity picks up again, leading to REM sleep. People who are asleep typically alternate between non-REM sleep and REM sleep throughout the night.
In contrast, people with narcolepsy quickly fall into REM sleep, often at unexpected moments. They also experience symptoms that occur in most people at other times of the sleep cycle. These include a relaxation of muscle tone (cataplexy), a temporary inability to move (sleep paralysis) and intense dreaming.
People with narcolepsy may also have other sleep disorders such as sleepwalking and/or mood disorders such as depression.
Patients may go many years before realizing that they have developed narcolepsy. They accept the daytime drowsiness as a part of life, not realizing it may be a more serious condition. Many do not seek treatment until other more disturbing symptoms such as cataplexy appear. Narcolepsy is incurable. However, effective forms of treatment can help patients to control their symptoms and to live full lives.
How is it diagnosed?
Patients will typically seek medical care when they find that overwhelming drowsiness is causing them to fall asleep at inappropriate times or preventing them from functioning effectively. In many cases, patients with narcolepsy go undiagnosed for many years, believing that their daytime drowsiness is normal, and do not seek medical assistance until symptoms such as cataplexy (a sudden, uncontrollable loss of muscle tone) occur.
Before diagnosing narcolepsy, a physician will perform a complete physical examination and compile a thorough medical history. Diagnosing narcolepsy can be difficult because symptoms related to the disorder mimic those of other conditions that may disrupt patterns of consciousness. These include depression, seizure disorders, fainting and simple tiredness resulting from inadequate sleep. In addition, other sleep disorders – such as sleep apnea (temporary cessation of breathing during sleep), insomnia (inability to sleep) or restless leg syndrome (sleep disorder characterized by leg discomfort during sleep) – can cause drowsiness similar to that experienced during narcolepsy.
If the physician determines that narcolepsy is a likely diagnosis, the patient may be referred to a sleep specialist. Patients may be asked to complete the Epworth Sleepiness Scale, in which they will be asked about a number of day-to-day situations and whether or not those circumstances typically make them sleepy. Another diagnostic tool called the Stanford Narcolepsy Questionnaire can provide important information about a patient’s narcolepsy in general and cataplexy in particular.
In many cases, patients will be asked to stay overnight at a sleep center and participate in a sleep study that allows experts to closely monitor their sleep habits. Prior to the visit, patients may be asked to keep a diary that tracks their sleep patterns for a week or two.
On the night of the visit to the sleep center, electrodes are placed on the patient’s scalp and other body parts as part of a procedure known as a polysomnogram. During this test, the electrical activity or movement of the heart, brain, muscles and eyes are measured. A polysomnogram helps indicate how much time elapses before a patient falls asleep. Shorter periods may indicate narcolepsy.
Patients may also undergo a multiple sleep latency test, which measures the length of time it takes a patient to fall asleep during the day. As part of this test, the patient is asked to take four or five naps spaced two hours apart. Experts observe how long it takes the patient to enter into rapid eye movement (REM) sleep. Patients with narcolepsy typically fall asleep much faster (less than five minutes) than those who do not have the disorder (who tend to fall asleep after 10 to 20 minutes).
Narcolepsy is formally diagnosed when a patient is unable to resist falling asleep on a daily basis for a period of at least three months. The patient must feel refreshed upon awakening and experience either cataplexy, recurrent episodes of REM sleep during the transition between sleep and wakefulness (as evidenced by the presence of <1>hypnagogic hallucinations or sleep paralysis), or both. Although a polysomnogram is not necessary to diagnose narcolepsy, most physicians will recommend one to identify specific symptoms of a patient’s condition and potentially help with treatment.
How is Narcolepsy treated?
Although there is no cure for narcolepsy, the disorder can be treated in a manner that minimizes symptoms and allows patients to live full lives. Stimulant drugs that arouse the central nervous system (CNS) can help patients remain awake during the day. Traditional stimulants may cause side effects such as nervousness and heart palpitations. Some patients may prefer to use a new type of stimulant medication called modafinil that appears to cause fewer side effects. Pregnant women who take medications to control narcolepsy may have to temporarily suspend the use of these drugs because their effect on a developing fetus is unknown.
Antidepressants are often prescribed for patients who experience cataplexy (a sudden loss of muscle tone), hypnagogic hallucinations (intense, frightening dreams that occur when patients are partially awake and are perceived as reality) and sleep paralysis (phenomenon marked by a temporary inability to move). These drugs suppress REM sleep, which helps lessen these symptoms. It is important to note that the U.S. Food and Drug Administration (FDA) has advised that antidepressants may increase the risk of suicidal thinking in some patients and all people being treated with them should be monitored closely for unusual changes in behavior.
In some cases, the drug sodium oxybate may be prescribed to improve the quality of sleep, although it has potential for abuse and its use is tightly controlled.
Patients are urged to remember that medications and lifestyle changes are intended to reduce symptoms and cannot be expected to eliminate them. Support groups and psychotherapy are available to help patients cope with their disorder.
Medications for the treatment of narcolepsy
Prozac (Fluoxetine), Celexa (Citalopram), Tofranil (Imipramine), Ambien (Zolpidem)
Activity
- Don't engage in any activity that carries the risk of injury from a sudden sleep attack. These include activities such as driving long distances, climbing ladders or working around dangerous machinery.
- Exercise can sometimes decrease the number of sleep attacks. Seek to achieve optimal physical fitness.
What might complicate it?
Narcolepsy has physical and social ramifications that can be debilitating or life threatening.
Predicted outcome
Treatment is directed at controlling or lessening the sleep attacks and associated symptoms. Narcolepsy is a life-long condition that can be controlled in an individual who follows the treatment plans.
Alternatives
Atonic seizures are very similar to the cataplectic attacks of narcolepsy. They usually are associated with other seizures and the individual loses consciousness, unlike narcolepsy.
Appropriate specialists
Sleep disorder clinic and neurologist.
Last updated 27 June 2015