Narcolepsy is a rare sleep disorder defined by excessive daytime sleepiness. An estimated 135,000 to 200,000 Americans have narcolepsy according to the National Institute of Neurological Disorders and Stroke. Narcolepsy symptoms usually begin between the ages of 7 and 25, though symptoms can begin at any age. Narcolepsy affects men and women equally.
In people with narcolepsy, the brain’s ability regulate sleep-wake cycles is impaired. There are two types of sleep in a normal sleep cycle: rapid eye movement (REM) sleep and non-REM (NREM) sleep. REM sleep is the dreaming stage of sleep. During REM sleep, people experience temporary muscle paralysis to prevent physical reactions or acting out dreams. In a normal, healthy sleep cycle, a person will enter REM sleep within an hour to 90 minutes of falling asleep. People with narcolepsy can enter REM sleep in just 15 minutes.
When the sleep cycle is well-regulated, REM sleep, NREM sleep, and being awake are separate, distinct states. For people with narcolepsy, the characteristics of REM sleep, NREM sleep, and wakefulness are less distinct, and people can experience symptoms normally associated with REM sleep when they’re awake.
There are four primary symptoms of narcolepsy — excessive daytime sleepiness (EDS), cataplexy, sleep paralysis, and hallucinations. However, only about 10 percent to 25 percent of people with narcolepsy experience all four primary symptoms. In addition to the primary symptoms of narcolepsy, people with the sleep disorder may experience many other symptoms related to disrupted sleep-wake cycles.
Excessive daytime sleepiness is the signature symptom of narcolepsy. People with narcolepsy may feel exhausted throughout the day, even if they’ve had a full night’s rest. Sometimes EDS causes people to have sleep attacks — where they involuntarily fall asleep. Some people with narcolepsy compare the exhaustion of EDS to what a person without narcolepsy might feel after being awake all night. Short naps tend to alleviate daytime sleepiness for a couple of hours.
Excessive sleepiness can manifest differently in children and adults. While adults may have sleep attacks, children may exhibit irritability, hyperactivity, and attention problems. Children may revert to the napping schedule of a younger child without being more alert or refreshed when waking.
Cataplexy is unique to type 1 narcolepsy, previously called narcolepsy with cataplexy. Cataplexy is a sudden episode of muscle weakness, usually triggered by anger, stress, excitement, or other strong emotions. Length and severity of cataplexy episodes vary. They can last a few seconds or a couple of minutes. A cataplexy episode can be mild, consisting of eyelid drooping, a slack jaw, or a dropped head. Episodes can also be more serious, where a person falls down. Some people experience cataplexy frequently, while others rarely have episodes. People remain awake during cataplectic episodes.
Stress and poor sleep can worsen cataplexy. In some cases, people experience status cataplecticus — repeated cataplexy episodes over a period of several hours. Status cataplecticus can also be caused by medication withdrawal. It’s believed that cataplexy occurs when the muscle limpness that occurs during REM sleep happens when a person is awake.
Type 1 narcolepsy is associated with low levels of a sleep-regulating hormone called hypocretin (sometimes called orexin). Low hypocretin is seen in about 90 percent of people with type 1 narcolepsy. Read more about causes of narcolepsy.
Sleep paralysis is an inability to move or speak, usually when first waking up, though it can happen when falling asleep. Sleep paralysis impacts between 25 percent and 50 percent of people with narcolepsy. Sleep paralysis usually only lasts a few seconds, but can last minutes on rare occasions. Sometimes people experience the sensation of suffocating when they have an episode of sleep paralysis. Sleep paralysis is related to a dysfunctional REM sleep cycle.
People with all types of narcolepsy can experience hallucinations when they wake up, called hypnopompic hallucinations, and hallucinations when they fall asleep, called hypnagogic hallucinations. Estimates of the prevalence of hallucinations vary widely, from 33 percent to 80 percent for hypnagogic hallucinations. Hallucinations can be extremely vivid and sometimes scary. It’s believed that hallucinations are similar to the dreams that a person experiences during REM sleep, except a person with narcolepsy may experience them while being partially awake.
Disrupted nighttime sleep (DNS) patterns are a frequent symptom of narcolepsy. Depending on the sleep study tool used, studies estimate that 30 percent to 95 percent of people with narcolepsy experience DNS. People with narcolepsy have a short sleep latency (amount of time it takes to fall asleep), but are often unable to stay asleep. People may wake up several times throughout the night and may be unable to fall back asleep for long stretches.
Sleep attacks are the irresistible need to sleep or an inability to stay awake. Sleep attacks are usually part of the excessive daytime sleepiness that people with narcolepsy experience. Sleep attacks can be as short as a few seconds or last for several minutes.
Sometimes people with epilepsy experience extremely short sleep episodes in the middle of an activity and continue the activity without being aware of what they are doing. Automatic behaviors are most likely to occur during routine activities. While the individual continues to perform the activity, functionality is impaired. This can be very dangerous if automatic behaviors occur when a person is driving.
Narcolepsy can have negative impacts on people’s mental health, social involvement, and cognition. Narcolepsy symptoms can make it difficult for people to meet social and work obligations and can limit activities like driving.
Depression is a common symptom of narcolepsy. A survey of 500 adults with narcolepsy in the United Kingdom found that nearly 57 percent reported depression symptoms. A study of 88 children with narcolepsy found that 25 percent experienced symptoms of depression.
There are several possible explanations for the prevalence of depression among people with narcolepsy. One potential explanation is the overlap of sleep patterns among people with depression and people with narcolepsy. People with both conditions experience a short onset of REM sleep and fragmented sleep. There is also emerging evidence that REM sleep can impact emotional processing. REM sleep patterns in people with narcolepsy may increase the weight of negative experiences in their emotional memory. Low levels of hypocretin may also contribute to depression.
Speak to your health care provider if you’re experiencing symptoms of depression. They can help you identify the right treatments and mental health professionals to support you.
People with narcolepsy may also experience symptoms of anxiety. A study of 60 individuals with epilepsy found that more than half experienced panic attacks and social phobia. In a study of 53 children and teens with type 1 narcolepsy, 45 percent had some degree of social impairment. Questions about anxiety and social avoidance were part of the assessment used to determine social functioning. The reasons for anxiety aren’t fully understood. Anxiety may be related to feeling out of control due to narcolepsy symptoms. Anxiety may also be related to low hypocretin levels.
Excessive daytime sleepiness, sleep attacks, automatic behaviors, and poor nighttime sleep may contribute to concentration and memory difficulties in people with narcolepsy. A 2017 review of eight studies of cognition in children with narcolepsy found that children with narcolepsy are at risk of cognitive difficulties related to attention, concentration, and decision-making. The small number of studies and the small sample size of many studies means more research is required to fully understand the cognitive impacts of narcolepsy.
Attention deficit hyperactivity disorder (ADHD) can occur in children with narcolepsy. One study found that ADHD symptoms were twice as common in children with narcolepsy than in children without narcolepsy.
Recent research indicates that sleep problems are related to ADHD. The precise reasons for this relationship aren’t fully understood. ADHD in people with sleep disorders may be related to fragmented sleep patterns and excessive daytime sleepiness. Because both people with type 1 and type 2 narcolepsy can have ADHD, hypocretin levels are believed to be unrelated to the presence of ADHD symptoms.
There is some evidence that children with narcolepsy who are obese may be at greater risk of developing anorexia or bulimia. Increased risk of eating disorders may be related to hormonal changes caused by narcolepsy.
Obesity is a common symptom in people with narcolepsy. It affects a higher proportion of children with narcolepsy than adults. As many as 50 percent to 74 percent of children with narcolepsy are overweight compared to 30 percent of adults. The reason for high rates of obesity in children with narcolepsy is not fully understood. One theory suggests the relationship between hypocretin and hormones that signal fullness to the body may contribute to weight gain.
Obesity in narcolepsy can impact the chances of developing related conditions like obstructive sleep apnea.
Precocious puberty is the early onset of puberty. In North America, precocious puberty is generally defined as puberty beginning before age 8 in girls and before age 9 in boys. In a study of 42 children and adolescents with narcolepsy, 17 percent showed signs of precocious puberty. The study also found that earlier narcolepsy symptom onset is associated with increased likelihood of precocious puberty. The precise reason for early puberty is not fully understood, however studies have suggested a relationship between lack of hypocretin and hormone dysfunction.