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Narcolepsy is a neurological condition most characterized by Excessive
Daytime Sleepiness (EDS). A narcoleptic will most likely experience
disturbed nocturnal sleep, confused with insomnia, and disorder of REM
or rapid eye movement sleep. It is one of the dyssomnias.
The term narcolepsy derives from the French word narcolepsie created in
1880 by the French physician Jean-Baptiste-Édouard Gélineau (1859-1928)
by combining the Greek narke numbness, stupor and lepsis attack,
seizure. [Source: entry Narcolepsy. in the Online Etymology Dictionary.
Douglas Harper, Historian. 18 Sep
2007.
Symptoms
The main characteristic of narcolepsy is overwhelming excessive daytime
sleepiness (EDS), even after adequate night time sleep. A person with
narcolepsy is likely to become drowsy or to fall asleep, often at
inappropriate times and places. Daytime naps may occur without warning
and may be physically irresistible. These naps can occur several times a
day. They are typically refreshing, but only for a few hours. Drowsiness
may persist for prolonged periods of time. In addition, night-time sleep
may be fragmented with frequent awakenings.
Four other classic symptoms of narcolepsy, which may not occur in all
patients, are cataplexy, sleep paralysis, hypnogogic hallucinations, and
automatic behavior. Cataplexy is an episodic condition featuring loss of
muscle function, ranging from slight weakness (such as limpness at the
neck or knees, sagging facial muscles, or inability to speak clearly) to
complete body collapse. Episodes may be triggered by sudden emotional
reactions such as laughter, anger, surprise, or fear, and may last from
a few seconds to several minutes. The person remains conscious
throughout the episode. Sleep paralysis is the temporary inability to
talk or move when waking up. It may last a few seconds to minutes. This
is often frightening but is not dangerous. Hypnagogic hallucinations are
vivid, often frightening, dreamlike experiences that occur while dozing,
falling asleep and/or while awakening. Automatic behavior means that a
person continues to function (talking, putting things away, etc.) during
sleep episodes, but awakens with no memory of performing such
activities. It is estimated that up to 40 percent of people with
narcolepsy experience automatic behavior during sleep episodes. Daytime
sleepiness, sleep paralysis, and hypnagogic hallucinations also occur in
people who do not have narcolepsy, more frequently in people who are
suffering from extreme lack of sleep. Cataplexy is generally considered
to be unique to narcolepsy.
In most cases, the first symptom of narcolepsy to appear is excessive
and overwhelming daytime sleepiness. The other symptoms may begin alone
or in combination months or years after the onset of the daytime naps.
There are wide variations in the development, severity, and order of
appearance of cataplexy, sleep paralysis, and hypnagogic hallucinations
in individuals. Only about 20 to 25 percent of people with narcolepsy
experience all four symptoms. The excessive daytime sleepiness generally
persists throughout life, but sleep paralysis and hypnagogic
hallucinations may not.
Although these are the common symptoms of narcolepsy, many (although
less than 40% of people with narcolepsy) also suffer from insomnia for
extended periods of time. This is most often from
An excess of sleep.
Use of self-medications such as energy drinks, or caffeinated drinks.
The symptoms of narcolepsy, especially the excessive daytime sleepiness
and cataplexy, often become severe enough to cause serious problems in a
person's social, personal, and professional life.
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. This sleep state, called REM
sleep (rapid eye movement sleep), is when most remembered dreaming
occurs. Associated with the EEG observed waves during REM sleep muscle
atonia is present (called REM atonia).
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 muscular control, sleep
paralysis, and vivid dreams — occur at other times in people with
narcolepsy. For example, the lack of muscular control can occur during
wakefulness in a cataplexy episode; it is said that there is intrusion
of REM atonia during wakefulness. Sleep paralysis and vivid dreams can
occur while falling asleep or waking up. Simply put, the brain does not
pass through the normal stages of dozing and deep sleep but goes
directly into (and out of) rapid eye movement (REM) sleep. This has
several consequences:
Nighttime sleep does not include much deep sleep, so the brain tries to
"catch up" during the day, hence EDS
May visibly fall asleep at any moment (such motions as head bobbing are
common)
People with narcolepsy fall quickly into what appears to be very deep
sleep
They wake up suddenly and can be disoriented when they do (dizziness is
a common occurrence)
They have very vivid dreams, which they often remember
People with narcolepsy may dream even when they only fall asleep for a
few seconds.
Causes
While the cause of narcolepsy has not yet been determined, scientists
have discovered conditions that may increase an individual's risk of
having the disorder. Specifically, there appears to be a strong link
between narcoleptic individuals and certain genetic conditions. One
factor that may predispose an individual to narcolepsy involves an area
of Chromosome 6 known as the HLA complex. There appears to be a
correlation between narcoleptic individuals and certain variations in
HLA genes, although it is not required for the condition to occur.
Certain variations in the HLA complex are thought to increase the risk
of an auto-immune response to protein producing neurons in the brain.
The protein produced, called hypocretin or orexin, is responsible for
controlling appetite and sleep patterns. Individuals with narcolepsy
often have reduced numbers of these protein-producing neurons in their
brains.
The neural control of normal sleep states and the relationship to
narcolepsy are only partially understood. In humans, narcoleptic sleep
is characterized by a tendency to go abruptly from a waking state to REM
sleep with little or no intervening non-REM sleep. The changes in the
motor and proprioceptive systems during REM sleep have been studied in
both human and animal models. During normal REM sleep, spinal and
brainstem alpha motor neuron depolarization produces almost complete
atonia of skeletal muscles via an inhibitory descending reticulospinal
pathway. Acetylcholine may be one of the neurotransmitters involved in
this pathway. In narcolepsy, the reflex inhibition of the motor system
seen in cataplexy is believed identical to that seen in normal REM
sleep.[citation needed]
In 2004 researchers in Australia induced narcolepsy-like symptoms in
mice by injecting them with antibodies from narcoleptic humans. The
research has been published in the Lancet providing strong evidence
suggesting that some cases of narcolepsy might be caused by autoimmune
disease.
Narcolepsy is strongly associated with HLA DQB1*0602 genotype. There is
also an association with HLA DR2 and HLA DQ1. This may represent linkage
disequilibrium.
Despite the experimental evidence in human narcolepsy that there may be
an inherited basis for at least some forms of narcolepsy, the mode of
inheritance remains unknown.
Some cases are associated with genetic diseases such as Niemann-Pick
disease or Prader-Willi syndrome.
Provigil is an anti-narcoleptic agent used to improve wakefulness in
patients with narcolepsy (sudden uncontrollable attacks of daytime
sleepiness). It may also be used to treat other conditions as determined
by your doctor. This medicine is a wake-promoting agent for the
treatment of excessive daytime sleepiness associated with narcolepsy.
Provigil has been proven to help people with narcolepsy stay awake.
Provigil improves daytime wakefulness, allowing people with narcolepsy
to participate in daily activities.
Provigil (modafinil) is used to improve wakefulness in patients with
narcolepsy, a condition that causes excessive daytime sleepiness.
Provigil is in a class of medications called central nervous system
(CNS) stimulants. Provigil does not cure narcolepsy and will only work
as long as you continue to take it. Provigil may be prescribed for other
uses; ask your doctor or pharmacist for more information..
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