Narcolepsy

Narcolepsy

Definition

Narcolepsy is a sleep disorder caused by the brain

normal sleep/wake cycles. People with narcolepsy have sleep episodes in

the daytime, hallucinations when falling asleep or awaking, and often

awaken at night.

’s inability to regulate

Description

Narcolepsy can affect people in any age group but may not be diagnosed

for as long as ten years after onset. It can be a disabling condition.

Because people with narcolepsy can fall asleep in the daytime in the

middle of other activities

equipment

with narcolepsy can fall behind in school or be judged as lazy students

even though they are of normal intelligence.

Having narcolepsy does not mean that people with the disorder sleep

more than other people. The disorder is better understood as a disturbance

of the normal boundaries between sleeping and waking rather than simply

sleeping too much. A normal adult who sleeps for about eight hours has

between four and six sleep cycles during that time. A sleep cycle is a period

of a type of sleep called non-rapid eye movement (NREM) sleep followed

by a period of rapid eye movement (REM) sleep. REM sleep is

characterized by increased brain activity, rapid movement of the eyes

below the lids, and sleep paralysis. People who say that they were having

a dream when they woke up have been awakened from REM sleep. In

normal adults, a sleep cycle is about 100

minutes of NREM sleep followed by 10

In narcolepsy, however, the patient

normal pattern. Instead, the person falls into REM sleep very shortly after

falling asleep. In addition, the short periods of sleep that the patient has

during the daytime are REM sleep. This abnormal occurrence of REM

sleep helps to explain such symptoms of narcolepsy as sleep paralysis and

cataplexy.

–110 minutes long, 80–100–20 minutes of REM sleep.’s sleep cycles do not follow this

Demographics

It is possible that narcolepsy affects more people than is presently known.

The rate of narcolepsy in the general population varies widely around the

world. In Israel, for example, only about one person per 500,000 is diagnosed

with narcolepsy whereas the rate in Japan is one person in every

600. In the United States, narcolepsy affects about one person in every

2,000. It is slightly more common in African Americans than in members

of other races.

Narcolepsy affects men and women equally. It is not thought to be

inherited. However, about 10 percent of Americans with narcolepsy have

a relative with the condition, but this percentage is low compared to

other disorders that are known to be purely genetic in origin.

Most cases of narcolepsy first appear in people between the ages of

ten and twenty-five years, but the disorder has been diagnosed in children

as young as three and in adults over fifty.

Causes and Symptoms

The basic cause of narcolepsy remains unknown. Progress has been made

since the late 1990s in identifying two pieces of the puzzle. The first is a

connection between narcolepsy and changes in a set of genes on chromosome

6 called the HLA complex. It is thought that changes in these genes

may be linked to the loss of cells in the brain that secrete hypocretin, a

protein that regulates the sleep/wake cycle. Researchers do not know

exactly what causes the loss of the brain cells that make hypocretin.

Because the HLA complex has been linked to other autoimmune disorders,

however, some doctors think that narcolepsy may be an autoimmune

disease. No one has been able to prove this theory as of late

2008, however. Other researchers think that the hypocretin-producing

cells may be damaged by some type of infection, but this theory has yet

to be proved.

Narcolepsy has four primary symptoms:

•

form of

drowsiness, or daytime episodes of sleep lasting half an hour or

longer.

Excessive daytime sleepiness (EDS). This symptom may take the“microsleeps” of a few seconds, a long-lasting feeling of

•

may result in slurred speech, sagging of the facial muscles, general

muscle weakness, inability to hold up one

knees, or loss of strength in the arms. Cataplexy is often triggered

by strong emotions, whether positive feelings like laughter or pleasant

surprise or negative emotions like fear, shock, or anger. Cataplexy

can last from a few seconds to as long as thirty minutes. The

person is awake and alert during an episode of cataplexy even

though he or she may appear unconscious to others.

Cataplexy. Cataplexy refers to a sudden loss of muscle tone that’s head, buckling of the

•

partial alertness that people have when they are waking up or

falling asleep. People with narcolepsy experience very vivid and

sometimes frightening dreams when they are half awake, and they

may mistake these dreams for reality.

•

move or speak while falling asleep or waking up. These episodes

last only one or two minutes and do not affect everyone with

narcolepsy, but they can be frightening to patients who do have

them.

Other symptoms experienced by some people with narcolepsy

include automatic behavior, in which the person performs a routine task

like sorting laundry or making a cup of coffee without conscious awareness

or later memory of the action. People with narcolepsy may also

thrash about in bed at night or act out their dreams by screaming or

waving their arms.

Sleep paralysis. Sleep paralysis refers to a temporary inability to

Diagnosis

The diagnosis of narcolepsy is often delayed because its symptoms

resemble those of such other disorders as depression, seizure disorders,

simple lack of sleep, or even illegal drug use. Early diagnosis is important

because the impact of the disorder on a person

relationships, and self-esteem can be severe. According to one study, 24

percent of adults with narcolepsy had to quit working and 18 percent

had been fired from their jobs because of the disease.

The diagnosis of narcolepsy is based on a combination of the

patient

testing in a sleep laboratory. The screening questionnaire that is used

most commonly is the Epworth Sleepiness Scale, or ESS, which was

developed in Australia in the early 1990s. The patient may also be asked

to keep a sleep diary for one or two weeks and wear a device called an

actigraph. The actigraph resembles a wrist watch and measures the person

sleep.

The patient will usually be tested overnight in a medical center

equipped with a polysomnograph. The polysomnograph is a machine

that measures the electrical activity of the heart and brain, breathing, and

eye movement while the patient is sleeping. Another sleep test is called

the multiple sleep latency test or MSLT. The patient is given a chance

to sleep every two hours during normal waking time. Observations are

made of the time taken to reach various stages of sleep. The MSLT

measures the degree of the patient

how soon REM sleep begins.

’s daytime sleepiness and also detects

Treatment

Treatment of narcolepsy involves a combination of medications, lifestyle

changes, and psychotherapy. The most common medications given are

stimulants that resemble amphetamine. It is important for persons taking

stimulants to notify their employer, because the drugs may show up

during pre-employment urine tests. Another type of drug that may be

prescribed is a drug called Xyrem, which controls cataplexy and helps

patients sleep better at night.

Lifestyle changes that are recommended for patients with narcolepsy

include:

•

and get up at the same time every day rather than changing their

sleeping schedule frequently.

Getting enough sleep at night. Patients are advised to go to bed

•

This practice helps to reduce daytime sleepiness.

Taking scheduled short naps at intervals during waking hours.

•

make it harder to sleep at night.

Avoiding the use of alcohol and tobacco. These substances can

•

bedtime helps many people with narcolepsy sleep better.

Getting regular exercise. Physical exercise four to five hours before

•

Being careful to avoid driving when tired or sleepy.

•

support from others with the same disorder is particularly helpful

to patients who may have waited years to be diagnosed and suffered

the loss of jobs, relationships, or educational opportunities

in the meantime.

Joining a narcolepsy support group. Finding understanding and

Prognosis

Narcolepsy cannot be cured but it is not a fatal disease. People with narcolepsy

can expect to live normal life spans (barring accidents). They can

also expect to lead normally productive and meaningful lives with proper

care and periodic consultations with a sleep specialist.

Prevention

There is no way known to prevent narcolepsy.

The Future

New drugs that will help narcoleptic patients remain awake were at the

clinical trial stage in late 2008. Some researchers in Germany were

experimenting with a nasal spray containing hypocretin that might be

beneficial to people with narcolepsy. Another possibility is the use of

stem cell transplants to restore the cells in the brain that make hypocretin,

but that approach will likely take several decades to be successful.

SEE ALSO

Restless legs syndrome; Sleep apnea

For more information

BOOKS

Sutton, Amy L., ed.

about Sleep and Sleep Disorders

Sleep Disorders Sourcebook: Basic Consumer Health Information. Detroit, MI: Omnigraphics, 2005.

PERIODICALS

Chen, Ingfei.

Times

health/healthguide/esn-narcolepsy-ess.html (accessed May 21, 2008).

“A Leap Forward, But Hurdles Remain in Narcolepsy.” New York, May 10, 2008. Available online at http://health.nytimes.com/ref/

WEB SITES

American Academy of Sleep Medicine (AASM).

online in PDF format at http://www.aasmnet.org/Resources/FactSheets/

Narcolepsy.pdf (updated 2006; accessed May 21, 2008).

Epworth Sleepiness Scale (ESS)

org/do2.php (accessed May 21, 2008). This is the screening

questionnaire that has been used since 1991 to evaluate people for

narcolepsy.

Narcolepsy Network.

http://www.narcolepsynetwork.org/faq.php (updated 2003; accessed May

21, 2008).

National Institute of Neurological Disorders and Stroke (NINDS).

Fact Sheet

narcolepsy/detail_narcolepsy.htm (updated January 11, 2008; accessed

May 21, 2008).

WORDS TO KNOW
Automatic behavior: Activity that a person with
narcolepsy can carry out while partially awake
but is not conscious of at the time and cannot
recall afterward.
Cataplexy: Sudden loss of tone in the voluntary
muscles.
Hypnagogic: Referring to the period of partial
alertness on the boundary between sleeping and
waking.
Hypocretin: A protein produced by certain brain
cells that promotes wakefulness and helps to
regulate the sleep/wake cycle. It is also known as
orexin.
Non-rapid eye movement (NREM) sleep: The first
phase of a sleep cycle, in which there is little or
no eye movement.
Rapid eye movement (REM) sleep: The phase of a
sleep cycle in which dreaming occurs; it is characterized
by rapid eye movements.
Sleep cycle: A period of NREM sleep followed by a
shorter phase of REM sleep. Most adults have
four to six sleep cycles per night.. Available online at http://www.narcolepsynetwork.Narcolepsy: Frequently Asked Questions. Available online atNarcolepsy. Available online at http://www.ninds.nih.gov/disorders/Fact Sheet: Narcolepsy. Available’s education, employment,’s history, the results of a screening questionnaire, and overnight’sHypnagogic hallucinations. Hypnagogic refers to the period of—including eating, driving, or operating heavy—they can be involved in serious accidents. Children or adolescents