Narcolepsy is a chronic sleep disorder, or dyssomnia. The condition is characterized by excessive daytime sleepiness (EDS) in which a person experiences extreme fatigue and possibly falls asleep at inappropriate times, such as while at work or at school. A narcoleptic will most likely experience disturbed nocturnal sleep and also abnormal daytime sleep pattern, which is often confused with insomnia. When a person with narcolepsy falls asleep they will generally experience the REM stage of sleep within 10 minutes; whereas most people do not experience REM sleep until after 30 minutes.
Cataplexy, a sudden muscular weakness brought on by strong emotions (though many people experience cataplexy without having an emotional trigger), is known to be one of the other problems that some narcoleptics will experience. Often manifesting as muscular weaknesses ranging from a barely perceptible slackening of the facial muscles to the dropping of the jaw or head, weakness at the knees, or a total collapse. Usually only speech is slurred, vision is impaired (double vision, inability to focus), but hearing and awareness remain normal. In some rare cases, an individual's body becomes paralyzed and muscles will become stiff.
The term narcolepsy derives from the French word ''narcolepsie'' created by the French physician Jean-Baptiste-Édouard Gélineau by combining the Greek narke ''numbness, stupor'' and lepsis ''attack, seizure.''
It is estimated that as many as 3 million people worldwide are affected by narcolepsy. In the United States, it is estimated that this condition afflicts as many as 200,000 Americans, but fewer than 50,000 are diagnosed. It is as widespread as Parkinson's disease or multiple sclerosis and more prevalent than cystic fibrosis, but it is less well known. Narcolepsy is often mistaken for depression, epilepsy, or the side effects of medications. It can also be mistaken for poor sleeping habits, recreational drug use, or laziness. Narcolepsy can occur in both men and women at any age, although its symptoms are usually first noticed in teenagers or young adults. There is strong evidence that narcolepsy may run in families; 8 to 12 percent of people with narcolepsy have a close relative with this neurologic disorder.
Narcolepsy has its typical onset in adolescence and young adulthood. There is an average 15-year delay between onset and correct diagnosis which may contribute substantially to the disabling features of the disorder. Cognitive, educational, occupational, and psychosocial problems associated with the excessive daytime sleepiness of narcolepsy have been documented. For these to occur in the crucial teen years when education, development of self-image, and development of occupational choice are taking place is especially damaging. While cognitive impairment does occur, it may only be a reflection of the excessive daytime somnolence.
The prevalence of narcolepsy is about 1 per 2,000 persons. Other medications used are codeine and selegiline. Another drug that is used is atomoxetine (Strattera), a non-stimulant and Norepinephrine reuptake inhibitor (NRI), that has little or no abuse potential. In many cases, planned regular short naps can reduce the need for pharmacological treatment of the EDS to a low or non-existent level.
Cataplexy and other REM-sleep symptoms are frequently treated with tricyclic antidepressants such as clomipramine, imipramine, or protriptyline, as well as other drugs that suppress REM sleep. Venlafaxine (branded as Effexor XR by Wyeth Pharmaceuticals), an antidepressant which blocks the reuptake of serotonin and norepinephrine, has shown usefulness in managing symptoms of cataplexy, however, it has notable side-effects including sleep disruption.
Gamma-hydroxybutyrate (GHB), more commonly known on the pharmaceutical market as Sodium Oxybate, or Xyrem (branded by Jazz Pharmaceuticals), is the only medication specifically indicated and approved for narcolepsy and cataplexy. Gamma-hydroxybutyrate has been shown to reduce symptoms of EDS associated with narcolepsy. While the exact mechanism of action is unknown, GHB is thought to improve the quality of nocturnal sleep by increasing the prevalence of slow wave (delta) sleep (as this is the time when the brain is least active and therefore most at rest and able to rebuild and repair itself physiologically). GHB appears to help sufferers much more effectively than the hypnotic class of medications typically used for insomnia (hypnotics tend to obstruct delta wave sleep), so it can be vital to be properly diagnosed as narcoleptic rather than insomniac. GHB was previously available on the open market as a dietary supplement but was reclassified a controlled substance in the United States due to pressure associated with the abuse of the chemical (it is infamously known as the date rape drug). It can currently only be legally acquired through prescription, after very specific diagnoses (typically for narcolepsy itself). Many healthcare providers, such as Welfare prescription plans in the USA, are unwilling to pay for the expensive drug and will instead present patients with stimulants.
Using stimulants to mask daytime sleepiness does not address the actual cause of the problem. Stimulants may provide some assistance with daytime activity, but the underlying cause will remain and potentially worsen over time due to the stimulant itself becoming an obstruction to delta wave sleep periods. Lifestyle changes involving reduced stress, more exercise (especially for overweight persons experiencing narcolepsy caused by sleep apnea and snoring) and less stimulant intake (such as coffee and nicotine) are likely to be ideal forms of assistive treatment. Some people with narcolepsy have a nocturnal body clock and are helped by selecting an occupation that properly coincides with their body's natural sleep cycle (such as sleeping in the day and working at night). This allows sufferers to avoid the need to force themselves into the more common 9 to 5 schedule that their body is unable to maintain, and avoids the need to take stimulants to remain active during the times when their bodies are inclined to rest.
In addition to drug therapy, an important part of treatment is scheduling short naps (10 to 15 minutes) two to three times per day to help control excessive daytime sleepiness and help the person stay as alert as possible. Daytime naps are not a replacement for nighttime sleep, especially if a person's body is natively inclined towards a nocturnal life cycle. Ongoing communication between the health care provider, patient, and the patient's family members is important for optimal management of narcolepsy.
Finally, a recent study reported that transplantation of hypocretin neurons into the pontine reticular formation in rats is feasible, indicating the development of alternative therapeutic strategies in addition to pharmacological interventions.
Further Reading
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