What is Narcolepsy?
Narcolepsy is a neurological sleep disorder where a person’s hypothalamas in the brain does not produce enough of a neurotransmitter called hypocretin.
What are the symptoms of Narcolepsy?
The four major signs and symptoms of narcolepsy are extreme daytime sleepiness, cataplexy (muscle weakness) while awake, and hallucinations and sleep paralysis during sleep. If you have narcolepsy, you may have one or more of these symptoms.
- What causes cataplexy?
Narcolepsy may have several causes.
- Autoimmune disorders. When cataplexy is present, the cause is most often the loss of brain cells that produce hypocretin. Although the reason for this cell loss is unknown, it appears to be linked to abnormalities in the immune system. Autoimmune disorders occur when the body’s immune system turns against itself and mistakenly attacks healthy cells or tissue. Researchers believe that in individuals with narcolepsy, the body’s immune system selectively attacks the hypocretin-containing brain cells because of a combination of genetic and environmental factors.
- Family history. Most cases of narcolepsy are sporadic, meaning the disorder occurs in individuals with no known family history. However, clusters in families sometimes occur—up to 10 percent of individuals diagnosed with narcolepsy with cataplexy report having a close relative with similar symptoms.
- Brain injuries. Rarely, narcolepsy results from traumatic injury to parts of the brain that regulate wakefulness and REM sleep or from tumors and other diseases in the same regions.
How is narcolepsy diagnosed?
- Polysomnogram (PSG or sleep study). The PSG is an overnight recording of brain and muscle activity, breathing, and eye movements. A PSG can help reveal whether REM sleep occurs early in the sleep cycle and if an individual’s symptoms result from another condition such as sleep apnea.
- Multiple sleep latency test (MSLT). The MSLT assesses daytime sleepiness by measuring how quickly a person falls asleep and whether they enter REM sleep. On the day after the PSG, an individual is asked to take five short naps separated by two hours over the course of a day. If an individual falls asleep in less than 8 minutes on average over the five naps, this indicates excessive daytime sleepiness. However, individuals with narcolepsy also have REM sleep start abnormally quickly. If REM sleep happens within 15 minutes at least two times out of the five naps and the sleep study the night before, this is likely an abnormality caused by narcolepsy.
How do you treat Narcolepsy?
Although there is no cure for narcolepsy, some of the symptoms can be treated with medicines and lifestyle changes. When cataplexy is present, the loss of hypocretin is believed to be irreversible and lifelong. Excessive daytime sleepiness and cataplexy can be controlled in most individuals with medications.
- Modafinil. The initial line of treatment is usually a central nervous system stimulant such as modafinil. Modafinil is usually prescribed first because it is less addictive and has fewer side effects than older stimulants. For most people these drugs are generally effective at reducing daytime drowsiness and improving alertness.
- Amphetamine-like stimulants. In cases where modafinil is not effective, doctors may prescribe amphetamine-like stimulants such as methylphenidate to alleviate EDS. However, these medications must be carefully monitored because they can have such side effects as irritability and nervousness, shakiness, disturbances in heart rhythm, and nighttime sleep disruption. In addition, health care professionals should be careful when prescribing these drugs and people should be careful using them because the potential for abuse is high with any amphetamine.
- Antidepressants. Two classes of antidepressant drugs have proven effective in controlling cataplexy in many individuals: tricyclics (including imipramine, desipramine, clomipramine, and protriptyline) and selective serotonin and noradrenergic reuptake inhibitors (including venlafaxine, fluoxetine, and atomoxetine). In general, antidepressants produce fewer adverse effects than amphetamines. However, troublesome side effects still occur in some individuals, including impotence, high blood pressure, and heart rhythm irregularities.
- Sodium oxybate. Sodium oxybate (also known as gamma hydroxybutyrate or GHB) has been approved by the U.S. Food and Drug Administration to treat cataplexy and excessive daytime sleepiness in individuals with narcolepsy. It is a strong sedative that must be taken twice a night. Due to safety concerns associated with the use of this drug, the distribution of sodium oxybate is tightly restricted.Lifestyle changes
Not everyone with narcolepsy can consistently maintain a fully normal state of alertness using currently available medications. Drug therapy should accompany various lifestyle changes. The following strategies may be helpful:
- Take short naps. Many individuals take short, regularly scheduled naps at times when they tend to feel sleepiest.
- Maintain a regular sleep schedule. Going to bed and waking up at the same time every day, even on the weekends, can help people sleep better.
- Avoid caffeine or alcohol before bed. Individuals should avoid alcohol and caffeine for several hours before bedtime.
- Avoid smoking, especially at night.
- Exercise daily. Exercising for at least 20 minutes per day at least 4 or 5 hours before bedtime also improves sleep quality and can help people with narcolepsy avoid gaining excess weight.
- Avoid large, heavy meals right before bedtime. Eating very close to bedtime can make it harder to sleep.
- Relax before bed. Relaxing activities such as a warm bath before bedtime can help promote sleepiness. Also make sure the sleep space is cool and comfortable.
How can W8MD help?
- Safety precautions, particularly when driving, are important for everyone with narcolepsy. People with untreated symptoms are more likely to be involved in automobile accidents although the risk is lower among individuals who are taking appropriate medication. EDS and cataplexy can lead to serious injury or death if left uncontrolled. Suddenly falling asleep or losing muscle control can transform actions that are ordinarily safe, such as walking down a long flight of stairs, into hazards.
W8MD’s Sleep Medicine Program uses state of the art technology including the convenient home sleep studies or in lab sleep diagnostic studies to diagnose and treat over 80 different sleep disorders including sleep apnea, narcolepsy, restless leg syndrome, insomnia to name a few.