Narcolepsy is a rare, long-term condition that causes a person to fall asleep suddenly at inappropriate times, such as while eating, moving about, or driving. There are two main types of narcolepsy: type 1 and type 2.
According to estimates, narcolepsy affects up to 200,000 people in the United States. However, this number may be higher because the condition is often undiagnosed or misdiagnosed. Narcolepsy typically starts in adolescence and is a lifelong condition. It can take several years for a person with narcolepsy to receive a diagnosis.
Keep reading to learn more about the types of narcolepsy, including their causes, symptoms, and treatments.
There are two main types of narcolepsy:
Type 1 narcolepsy
Type 1 narcolepsy is also known as narcolepsy with cataplexy, which is a temporary loss of muscle control. People with type 1 narcolepsy often have low levels of a brain hormone called hypocretin, also known as orexin.
Type 1 narcolepsy may cause cataplexy in response to sudden emotions, resulting in a feeling of physical weakness or even causing a person to collapse. People with this condition may also have excessive sleepiness during waking hours.
Type 2 narcolepsy
This type is also known as narcolepsy without cataplexy, as people with type 2 narcolepsy do not usually experience the loss of muscle control associated with type 1 narcolepsy. However, they do experience excessive sleepiness.
People with type 2 narcolepsy usually have normal levels of hypocretin.
Researchers believe that low levels of a naturally occurring hormone called hypocretin are the main cause of type 1 narcolepsy. Hypocretin helps the brain regulate sleep cycles.
Certain factors can cause hypocretin levels to lower, triggering narcolepsy. These include:
- Autoimmune disorders: Autoimmune disorders occur when the body produces antibodies, which attack healthy cells and tissues. Some
studieshave shown that people with narcolepsy produce antibodies that attack a protein called TRIB2. The part of the brain responsible for producing hypocretin is the same part that makes TRIB2. The National Organization for Rare Disorders (NORD) in the U.S states that there is increasing evidence to suggest that narcolepsy is an autoimmune disorder.
- Genetic history: Although narcolepsy is not a genetic condition, researchers believe that 1 in 10 people with the disorder have a close relative with the same symptoms.
- Injury to the brain: Although rare, injuries to the parts of the brain responsible for regulating sleep patterns could cause hypocretin levels to become low. Injury could be due to trauma, tumors, or brain disease.
Other possible causes of or triggers for type 1 or type 2 narcolepsy may include:
- hormonal changes, such as those that occur in puberty or the menopause
- major psychological stress
- an infection, such as swine flu or a streptococcal infection
- the flu vaccine Pandemrix — a
2013 studyfound that between 1 in 57,500 and 1 in 52,000 people developed narcolepsy after having the vaccine during a swine flu epidemic in the United Kingdom
- a sudden change in regular sleep patterns
However, more research is necessary to confirm these influencing factors.
The prevalence of type 2 narcolepsy is uncertain because it is not as well-studied as type 1 and is harder to diagnose. It typically presents with similar symptoms to type 1 narcolepsy, but these symptoms may change over time. Its causes are also less clear to experts. In fact, the NORD states that the exact cause of type 2 narcolepsy is unknown.
Some experts argue that type 2 narcolepsy might be an incorrect term to use. For example, a
The authors of the study suggest, therefore, that doctors may sometimes be confusing type 2 narcolepsy with other sleep disorders. They have called for more research involving people presenting with type 2 narcolepsy to understand the classification better.
Not everyone with type 1 or type 2 narcolepsy experiences the same symptoms. The severity and frequency of symptoms may also vary greatly among individuals.
Excessive daytime sleepiness
Most people with type 1 or type 2 narcolepsy will experience feelings of drowsiness during waking hours, which can make focusing and concentrating on tasks difficult. The duration of nighttime sleep has no effect on excessive daytime sleepiness.
Alongside excessive sleepiness, many people with narcolepsy will experience sudden periods of falling asleep, which can happen at any time. These so-called sleep attacks can last anywhere from a few seconds to several minutes and may occur up to several times a day.
Sleep paralysis is a temporary inability to move or speak while falling asleep or waking up. Although it may seem very similar to cataplexy, sleep paralysis only happens at the edges of sleep. It may last just a few seconds or persist for minutes.
As with sleep paralysis, people with narcolepsy who experience hallucinations often report seeing or hearing things that are not really there when falling asleep or waking up.
Other symptoms of narcolepsy may include:
- problems with memory
- automatic behavior, which refers to continuing a task or activity with no memory of it afterward
- fragmented sleep and insomnia
Cataplexy, in type 1 narcolepsy
Cataplexy is the loss of muscle control in the body. Sudden or strong emotions, such as laughter, excitement, fear, or stress, can trigger it. People who are experiencing cataplexy may find that their jaw drops, their speech becomes slurred, or they lose control of their limbs.
An attack of cataplexy may last anywhere from a few seconds to several minutes. People may experience an attack rarely or many times a day.
There is currently no cure for narcolepsy. However, people can manage the condition with medication and some lifestyle adjustments.
A person’s symptoms will determine their treatment options.
Excessive daytime sleepiness
Doctors commonly prescribe a stimulant for the central nervous system, such as modafinil (Provigil), or an amphetamine-like stimulant, such as methylphenidate (Ritalin).
However, a newer medication called solriamfetol (Sunosi) — a selective dopamine and norepinephrine reuptake inhibitor with wake-promoting effects — may become a reasonable first-line choice for treating sleepiness in narcolepsy in certain individuals.
The National Institute of Neurological Disorders and Stroke states that certain antidepressants are effective in controlling cataplexy. In particular, limited clinical trial data suggest that antidepressants that selectively inhibit the reuptake of norepinephrine or serotonin may substantially reduce cataplexy with relatively few side effects.
A doctor may also sometimes prescribe a strong sedative called sodium oxybate (Xyrem). Oxybates markedly reduce cataplexy and, therefore, are a good choice for people with severe cataplexy. The reduction in cataplexy develops over several weeks of treatment, so doctors should adjust people’s dosages slowly.
Another option is a medication called pitolisant (Wakix), which can reduce cataplexy. It serves as an alternative to oxybates for people whose cataplexy does not respond adequately to REM sleep-suppressing antidepressants.
The following lifestyle changes may also help ease the symptoms of narcolepsy:
- keeping a regular sleep schedule, which involves going to sleep and rising at the same time each day
- taking regular naps during the day, if possible
- maintaining an active and healthy lifestyle with plenty of physical exercise
- choosing relaxing activities before bedtime, such as a warm bath
- avoiding caffeine, alcohol, and smoking, particularly before bed
- avoiding cold and allergy medications that induce drowsiness
- talking with family, friends, and healthcare professionals about the condition to ease any stresses or fears
There are two types of narcolepsy: type 1 and type 2.
The symptoms of both types of narcolepsy include excessive sleepiness, which can come on suddenly, as well as sleep paralysis and hallucinations.
However, while people with type 1 narcolepsy also experience a temporary loss of muscle control called cataplexy and have low levels of hypocretin, these effects do not occur in type 2 narcolepsy. If a person with type 2 later develops cataplexy or low hypocretin, doctors will reclassify their diagnosis as type 1.
There is currently no cure, but medication and lifestyle adjustments may help control the symptoms.