Narcolepsy is a chronic sleep disorder resulting from the brain's inability to regulate sleep-wake cycles. At various times throughout the day, people with narcolepsy experience the fleeting urge to sleep. If the urge becomes overwhelming, patients fall asleep for periods lasting from a few seconds to several minutes. In rare cases, some people may remain asleep for an hour or longer. There is no known cure for narcolepsy.
Understanding Sleep States
Normally, when an individual is awake, brain waves show a regular rhythm. When a person first falls asleep, the brain waves become slower and less regular. This sleep state is called non-rapid eye movement (NREM) sleep. After about an hour and a half of NREM sleep, the brain waves begin to show a more active pattern again, even though the person is in deep sleep. This sleep state, called rapid eye movement (REM) sleep, is when dreaming occurs.
In narcolepsy, the order and length of NREM and REM sleep periods are disturbed, with REM sleep occurring at sleep onset instead of after a period of NREM sleep. Thus, narcolepsy is a disorder in which REM sleep appears at an abnormal time. Also, some of the aspects of REM sleep that normally occur only during sleep -- lack of muscle tone, sleep paralysis, and vivid dreams -- occur at other times in people with narcolepsy. For example, the lack of muscle tone can occur during wakefulness in a cataplexy episode. Sleep paralysis and vivid dreams can occur while falling asleep or waking up.
The cause of narcolepsy remains unknown. It is likely that it involves multiple factors interacting to cause neurological dysfunction and sleep disturbances.
Narcoleptic sleep episodes can occur at any time, and thus can prove profoundly disabling. People may involuntarily fall asleep while at work or at school, when having a conversation, playing a game, eating a meal, or, most dangerously, when driving an automobile or operating other types of potentially hazardous machinery.
In addition to excessive and overwhelming daytime sleepiness, there are three other major symptoms that frequently characterize narcolepsy:
- Cataplexy, or the sudden loss of voluntary muscle tone
- Vivid hallucinations during sleep onset or upon awakening
- Brief episodes of total paralysis at the beginning or end of sleep.
Contrary to common belief,
people with narcolepsy do not spend a substantially greater proportion of their time asleep during a 24-hour period than do normal sleepers. In addition to experiencing daytime drowsiness and involuntary sleep episodes, most patients also experience frequent awakenings during nighttime sleep. For these reasons, narcolepsy is considered to be a disorder of the normal boundaries between the sleeping and waking states.
Diagnosing narcolepsy is relatively easy when all the symptoms are present. But if the sleep attacks are isolated and cataplexy is mild or absent, it is more difficult to diagnose.
If a person has possible symptoms, the doctor will do a physical exam and ask about the patient's personal and family medical history. The doctor will also recommend additional tests in order to make a narcolepsy diagnosis.
Two tests that are commonly used in diagnosing narcolepsy are the polysomnogram and the multiple sleep latency test.
Narcolepsy is not usually diagnosed until 10 to 15 years after the first symptoms appear. This unusually long lag time is due to several factors, including the disorder's subtle onset and the variability of
narcolepsy symptoms. Equally important, however, is the fact that the public is largely unfamiliar with narcolepsy, as are many health professionals. When symptoms initially develop, people often do not recognize that they are experiencing the onset of a distinct neurological disorder and thus fail to seek medical treatment.
Although there is no cure for narcolepsy, treatments are available to help reduce the various symptoms of the disorder.
Treatment depends on the severity of the symptoms, and it may take weeks or months to work out an optimal regimen. Complete control of sleepiness and cataplexy is rarely possible. Also, the narcolepsy treatment can be modified as symptoms change.
Treatment is primarily with narcolepsy medications, but lifestyle changes are also important
(see Coping With Narcolepsy).
Depending on the symptoms, common narcolepsy drugs include:
(Click Narcolepsy Treatment for more information.)
None of the currently available narcolepsy medications enables
people with narcolepsy to consistently maintain a fully normal state of alertness. But excessive daytime sleepiness and cataplexy, the most disabling symptoms of narcolepsy, can be controlled in most patients with drug treatment.
Whatever the age of onset, patients find that their
narcolepsy symptoms tend to get worse over the two to three decades after the first symptoms appear. Many older patients find that some daytime symptoms decrease in severity after age 60.
