Narcolepsy is a brain disorder that involves poor control of the sleep-wake cycles.
There are several causes of narcolepsy and all result in low levels of hypocretin. Hypocretin is a neurotransmitter or signaling chemical which promotes wakefulness. Some cases of narcolepsy are due to defects in the genes which prevent normal production of hypocretin. Other cases are due to a loss of the cells that produce hypocretin in the brain. This loss is usually the result of an autoimmune process *which means that the body’s own immune system attacks these cells.)
Symptoms of narcolepsy include extreme daytime sleepiness and/or sudden bouts of sleep that can strike at any time. These sleep attacks usually last from a few seconds to several minutes. Other symptoms of narcolepsy include cataplexy, which is a sudden loss of voluntary muscle tone while awake. This may make a person become weak and unable to move or fall unexpectedly. Experiencing vivid dream-like images or hallucinations is also associated with this condition. Some persons with narcolepsy also undergo total paralysis just before falling asleep or just after waking up (sleep paralysis).
Obesity is another symptom of narcolepsy because many patients suddenly gain weight after developing this condition.
The polysomnogram (PSG) is a diagnostic test that is used to confirm the diagnosis of narcolepsy. This overnight test takes continuous measurements while the patient is asleep to document abnormalities in the sleep cycle. It also records the heart rate, respiratory rate, electrical activity in the brain using electroencephalography and nerve activity in muscles using electromyography. The PSG can determine whether an individual’s REM sleep occurs at abnormal times in the sleep cycle and it can rule out other conditions that cause symptoms that are similar to those of narcolepsy.
Another test used to make the diagnosis is the multiple sleep latency test (MSLT). This test is done during the day to measure an individual’s tendency to fall asleep and to determine whether elements of REM sleep occur inappropriately during the waking hours. During this test the individual is asked to take four or five short naps which are usually 2 hours apart during the course of the day. The “sleep latency” or the time it takes for them to fall asleep is measured. The normal is usually 12 minutes or longer and persons with a latency period of 8 minutes or less are diagnosed to have excessive daytime sleepiness.
There is no cure for narcolepsy but some of its symptoms can be controlled with medicines. Medications used to treat it that have been approved by the U.S. Food and Drug Administration (FDA) include the central nervous system alerting agent Modafinil.
Oxybate is another medication which has FDA approval for the treatment of narcolepsy. The amphetamine-like stimulant methylphenidate is also used to reduce excessive daytime sleepiness and the frequency of sleep attacks.
Common side effects of these medications include irritability, nervousness, shakiness, disturbances in heart rhythm, upset stomachs, nighttime sleep disruption and anorexia. Some patients develop tolerance to these medications and thus require increased dosages for them to remain effective.
The tricyclic antidepressants (TCAs) imipramine, desipramine, clomipramine and protriptyline are used to control cataplexy. Selective serotonin reuptake inhibitors (SSRIs) and noradrenergic reuptake inhibitors like venlafaxine, fluoxetine and atomoxetine are also used for the same purpose. Side effects of these antidepressants include impotence, high blood pressure and heart rhythm irregularities.
Sodium oxybate, which is a strong sedative, is also used to treat narcolepsy. It induces sleep and reduces the symptoms of daytime sleepiness and cataplexy. Gamma hydroxybutyrate (GHB or Xyrem) is also used to treat this condition.
Behavioral modifications are used to treat narcolepsy by helping improve the quality of nighttime sleep to combat excessive daytime drowsiness and fatigue. Helpful strategies include maintaining a regular sleep schedule by going to bed and waking up at the same time. Avoiding heavy meals and alcohol or caffeine containing beverages before bedtime can also improve sleep quality. Exercising for 20 minutes five hours before bedtime also improves sleep quality and can help prevent the weight gain associated with narcolepsy.
Treatment for narcolepsy is extremely important because without it the condition can adversely affect daily activities. For example, undiagnosed and/or untreated patients can fall asleep while operating machines or when driving.
Current research on narcolepsy includes the retraction by Stanford researchers of the findings of a study that had linked the H1N1 influenza virus to narcolepsy in 2013 since they were unable to replicate some of the reported results.
Support groups for narcolepsy include the Narcolepsy Network whose website is http://narcolepsynetwork.org/ and address is 129 Waterwheel Land North Kingstown, RI 02852. They can also be reached via email at firstname.lastname@example.org or by phone at 888 292 6522 and faxed at 401 633 6567.