Narcolepsy is a chronic neurological condition that disrupts the normal sleep-wake cycle. People with this sleep disorder can experience overwhelming fatigue and uncontrollable sleepiness; they nap or fall asleep often throughout the day and can lapse into fully unplanned sleep at any time. They may also take multiple "micro-naps," lasting just a few seconds at a time. During severe bouts of sleepiness, they may continue with their normal activities in a kind of automatic state, but may feel dazed and have no memory of engaging in the activity.
In many cases, people with narcolepsy also experience cataplexy, or sudden muscle weakness or paralysis. These disturbing episodes are often preceded by strong emotions—most commonly laughter but also anger, fear, or excitement; a person may laugh boisterously, for example, and then experience a sudden loss of muscle tone as their knees buckle or their head drops. Cataplexy episodes may last seconds or a few minutes, but they resolve instantly, and the individual remains conscious and aware throughout, even as their head bobs, their jaw drops, or they collapse to the ground.
Narcolepsy typically develops in children and young adults and rarely makes a first appearance later in life. The onset may be gradual or sudden. While the severity of symptoms may change over time, narcolepsy is a chronic, lifelong condition but treatment can help to address symptoms.
The core symptom of narcolepsy is the incidence of frequent recurring daytime naps or lapses into sleep. For a diagnosis to be made, according to the DSM-5, this excessive sleepiness must be chronic, occurring daily or at least three times per week for at least three months. Individuals may also experience bouts of sleep paralysis just before falling asleep or waking up.
For those experiencing frequent symptoms of narcolepsy, the condition can be formally diagnosed by a sleep specialist after an overnight sleep study. Often a clinician will also check a patient's levels of the hormone hypocretin, which helps to regulate both wakefulness and appetite, as a hypocretin deficiency is common in people with narcolepsy.
When cataplexy is a symptom of narcolepsy, as it typically is, those brief episodes of sudden loss of muscle tone after strong emotional moments, with retention of consciousness, must occur at least a few times a month for a diagnosis to be made. Some neurological research suggests that the particular repeated fluctuations of muscle activity and vocalizations that laughter produces make it especially likely to trigger cataplexy in individuals with hypocretin deficiency. Many sleep specialists, therefore, will try to confirm that a patient's cataplexy can be triggered by laughter before making a diagnosis.
When cataplexy occurs less than once a week, naps are needed only once or twice a day, and nocturnal sleep is less disturbed, the condition may be diagnosed as mild. A diagnosis of moderate narcolepsy can be made when cataplexy occurs daily or every few days, multiple daily naps are needed, and nocturnal sleep is more often disturbed. Severe cases involve multiple daily cataplexy attacks that are drug-resistant, with nearly constant sleepiness, and highly disturbed nocturnal sleep.
Symptoms of narcolepsy may arise concurrently with bipolar disorder, depression, and anxiety disorders. A sudden aggravation of narcoleptic symptoms may indicate the presence of sleep apnea.
It can have a significant negative effect. As they struggle with exhaustion and sleep disruption, children and adolescents with narcolepsy often develop aggression or other behavioral problems that make friendships a challenge. At any age, an individual may experience social isolation because of episodes of cataplexy, or they may avoid social commitments out of fear that episodes could occur. As one enters college and the workforce, increased professional and social demands may reduce one’s available time for nighttime sleep, further disrupting the sleep-wake cycle and exacerbating symptoms. The effort to exert control over one’s emotions to avert cataplexy can also make social connections a struggle.
Approximately 20 to 60 percent of people with narcolepsy experience vivid hallucinations upon falling asleep (hypnagogic hallucinations) or just after awakening (hypnopompic hallucinations). These vivid hallucinations are often very scary. During the hallucinations, a person may be conscious but unable to move or speak even if the images are terrifying. After waking, it may take several minutes to readjust to reality and understand that the frightening or threatening situations were only hallucinations.
These episodes are not exactly nightmares—although people with narcolepsy, especially children, appear to be more prone to nightmares than others—but REM-stage dreams experienced when the person is semi-awake. Young children with narcolepsy find it especially difficult to separate these scary images from their everyday reality.
The presence of hallucinations, coupled with the fact that extreme fatigue is a symptom of other mental health disorders, sometimes leads people with narcolepsy to be misdiagnosed, which is why those experiencing symptoms are best seen by a neurologist or sleep specialist
Narcolepsy is an abnormality in rapid eye movement (REM) sleep, usually the most restorative sleep stage. In most people, weak muscle tone and vivid, intense dreams are regular features of REM sleep, but for those with narcolepsy, these events occur during waking moments.
The cause of the condition is not fully understood, but it appears to be brought on by genetic and/or environmental factors. People with a first-degree relative (a parent or sibling) who has narcolepsy are 10-to-40 times more likely to develop narcolepsy than others: Their prevalence is 1 to 2 percent as opposed to less than .04 percent for the general population.
A deficiency of the neuropeptide hypocretin, one of a group of molecules that help neurons in the brain communicate with one another, typically leads to the onset of narcolepsy, as lower levels disrupt an individual’s sleep-wake cycle. Hypocretin levels can be measured by a clinician.
Narcolepsy can also be caused by head trauma, autoimmune disorders, and sudden changes in sleep-wake patterns.
The National Institutes of Health estimates that between 135,000 and 200,000 people in the United States have narcolepsy, indicating a rate of less than .01 percent. However, the disorder is widely believed to be underdiagnosed and some researchers believe its true incidence is more likely .02 to .04 percent of the general population. Narcolepsy occurs in roughly similar numbers of men and women, although some research suggests men may be more prone to it.
A deficiency of the hormone hypocretin is a frequent cause of narcolepsy, but this neuropeptide also influences appetite, and its deficiency also makes individuals prone to nocturnal eating and overeating; obesity, therefore, is common among people living with the condition. Rapid weight gain is especially common with the sudden onset of narcolepsy in children.
There is no known cure for narcolepsy, but several treatment options can address the symptoms and improve individuals’ quality of life. Simulants such as methylphenidate or amphetamine and antidepressants such as SSRIs may be prescribed to reduce daytime drowsiness and control cataplexy and the medications are often effective.
Sleep specialists typically will suggest lifestyle changes to limit symptoms as well, such as taking regularly scheduled short naps, maintaining a consistent sleep schedule, avoiding caffeine and alcohol, not smoking, and exercising daily.
Individuals with narcolepsy may find that their driving and working are impaired and should avoid jobs that put themselves or others in danger, such as conducting a train or working with machinery. When medication, therapy, or lifestyle adjustments have one’s narcolepsy under control, they may be more comfortable behind the wheel but should still avoid driving long distances alone.