Narcolepsy – Definition, Causes, Symptoms, Diagnosis, and Treatment

Narcolepsy is a chronic neurological disorder that affects the brain’s ability to regulate the sleep/wake cycle. People who are affected by this condition often feel excessively tired during the day, even if they got enough sleep at night. This excessive sleepiness is not ordinary and feels more like a sleep attack, where the affected person cannot suppress the feeling of fatigue, and they may nod off for a few seconds to several minutes at a time.

Narcolepsy is a chronic neurological disorder that affects the brain’s ability to regulate the sleep/wake cycle. People who are affected by this condition often feel excessively tired during the day, even if they got enough sleep at night. This excessive sleepiness is not ordinary and feels more like a sleep attack, where the affected person cannot suppress the feeling of fatigue, and they may nod off for a few seconds to several minutes at a time.

People with narcolepsy experience changes in the architecture of their sleep, especially in REM stages. Rapid eye movement (REM) sleep usually occurs every 60 to 90 minutes in people with regular sleep cycles, but in those affected by narcolepsy, it can happen only 10 minutes after falling asleep. Additionally, people may experience cataplexy, which is described as the weakness of muscles that enables a person to move while awake. This state is similar to the paralyzing of the muscles that happen during the REM stage, but since the brain has lost the ability to regulate sleep and wake cycle, it can randomly occur during wakefulness.

It is estimated that 135.000 to 200.000 people are affected by narcolepsy in the United States. However, some experts believe that the condition is underdiagnosed because it is often mistaken with psychiatric disorders, and that the number can be much higher. It affects males and females equally, and the first symptoms usually appear between the ages of 7 and 25.

The goal of this article is to educate people on the causes, symptoms, and the treatment of narcolepsy. Affected people go through many relationship, work, academic, and social problems because of the sleep attacks, and that can often lead to the feeling of embarrassment and impaired mental health. 

Types of Narcolepsy

There are two main types of narcolepsy:

  • Type 1 or narcolepsy with cataplexy. It is characterized by a sudden muscle weakness that enables a person to move. Strong emotions often trigger these events, and they can be dangerous if they happen during certain activities such as driving. The main symptom of this type 1 narcolepsy is daytime sleepiness, but people can also experience sleep hallucinations and sleep paralysis. Individuals affected by this most commonly have low levels of brain hormone hypocretin.
  • Type 2 or narcolepsy without cataplexy. It is also characterized by excessive daytime sleepiness, but unlike type 1, there are no sleep attacks and cataplexy. People with this condition often have less severe symptoms and normal levels of hypocretin.

A disorder known as secondary narcolepsy can arise from an injury to the hypothalamus, a brain region that plays a significant role in regulating sleep. Besides the standard symptoms, these individuals can also experience severe neurological problems and sleep for prolonged periods each night (more than 10 hours).


The symptoms start in early life, in most cases in the teenage period. Unfortunately, it is a lifelong condition, but it doesn’t necessarily get worse with age. Some symptoms improve over time, especially if the person follows the guidelines for narcolepsy management. The excessive daytime sleepiness is present in all the patients, but all other symptoms are only experienced by 10 to 25 percent of affected individuals. Symptoms include:

  • Excessive daytime sleepiness (EDS) is present in all individuals, and it’s the most obvious symptom. EDS is persistent even if the person seems to get enough sleep during the night and feel well-rested in the morning. Unlike with other sleeping disorders, EDS in narcolepsy manifests through the sudden urge to fall asleep, and these sleep attacks come rather unexpectedly. In between these events, a person has normal levels of alertness, especially if they are partaking in an activity that requires their close attention.
  • Cataplexy is defined by a sudden loss of muscle tone that leads to muscle weakness and inability to move while the person is awake. It is often triggered by strong emotions such as anger, fear, excitement, laughter, or stress. The onset of cataplexy can be years after the start of EDS, and while some people can only experience a few attacks in their lifetime, others may have many each day. In a small percentage of cases, cataplexy can be the first symptom to appear, and these people are usually misdiagnosed with a seizure disorder. Most of the attacks are on the mild side, where the person feels weakness in limited muscles in their body, and it quickly passes after a few moments. In most severe cases, the affected person’s whole body can collapse, leaving them unable to move, speak, or even open their eyes. But what distinguishes cataplexy from other seizure disorders is that people remain fully conscious even during the most severe attacks. These episodes can last anywhere from a few seconds to several minutes, and they can be terrifying, but in most cases are not dangerous if a person can sense them and find a safe place to collapse.
  • Sleep paralysis is described by the temporary inability to move or speak while falling asleep or waking up. It usually lasts from a few seconds to a few minutes, and it is similar to REM induced paralysis, only a person is awake during this event. It resembles cataplexy, and the only difference is that it occurs at the edges of sleep. These events can be pretty scary and troubling, and some people can be mentally affected for an extended period after the episode. In most cases, people fully recover after they are regained the ability to move and speak. 
  • Hallucinations are present in a small number of people, and they can sometimes accompany sleep paralysis. Hallucinations can be very vivid and frightening, and while in most cases they are primarily visual, other senses can be involved as well.
  • Fragmented sleep and insomnia. Individuals with narcolepsy are very sleepy during the day, but at night they often experience difficulties staying asleep. Sleep maintenance can be affected by vivid dreams, sleep apnea, acting out while dreaming, periodic limb movement, and it can lead to the development of insomnia.
  • Automatic behaviors. Individuals affected by this condition often experience microsleeps during the day that usually last a few seconds. A person briefly falls asleep while doing some type of activity, and they continue doing it without being conscious or aware of the action. That mostly happens with routine activities such as writing, typing, and driving. After they wake up, they have no recollection of their actions, but they can recognize them by the impaired performance. If they were writing, their handwriting could degenerate to the point of no recognition, the text they were typing doesn’t make sense, or they might get lost while driving, or even worse, have an accident. After people wake up from these episodes, they usually feel refreshed, and their fatigue and sleepiness disappear for a short period.

What Causes Narcolepsy?

There are several known causes of this disorder. Almost all people with type 1 narcolepsy have lower levels of a brain hormone hypocretin (orexin), which plays a vital role in regulating REM sleep and promoting wakefulness. Low levels of hypocretin do not describe type 2 narcolepsy, and its causes are not well understood. And even though we know that the balance of this naturally appearing hormone dictates the development of the condition, we are not entirely sure how it all works and why it happens. Several factors cause lower hypocretin levels, and they include:

  • Autoimmune disorders occur when the person’s immune system doesn’t function properly, turns against itself, and then attacks healthy cells and tissues in the body. Since the cause in most cases is loss of the neurons that produce hypocretin, it appears that it is linked with abnormalities in the immune system. 
  • Hereditary factors seem to play a significant role as well, as around 10% of narcolepsy patients report to have a close relative with similar symptoms. However, most of the cases are sporadic, meaning that there is no family history of the disease. That probably means that the person could be genetically predisposed to developing the condition, but that it also depends on the environmental factors.
  • Brain injuries can cause narcolepsy. Usually, when the hypothalamus is affected, symptoms can develop. Tumors and other diseases that affect this region can have the same effect.

Related Conditions

Idiopathic hypersomnia is a condition that falls into the same category of sleep disorders as narcolepsy (hypersomnias). It is characterized by episodes of extreme sleepiness that have no identifiable cause. It is different than narcolepsy because the patients never develop cataplexy, and they don’t have sudden sleep attacks. Many individuals experience prolonged periods of rest (more than 10 hours), and excessive sleepiness can disrupt many aspects of life. Standard treatment includes behavioral therapy and certain medications.

Obstructive sleep apnea is a sleep-related breathing disorder that is described by the temporary interruption and cessation of airflow. It is caused by the blockage in the upper airway, and the person affected by it often wakes up during the night short of breath and painting. The most visible sign of sleep apnea is loud snoring, and others include excessive daytime sleepiness, sleep fragmentation, irritability, poor concentration, and impaired cognition. Obesity and neck size are the most common causes of this disorder, and if untreated, it could lead to high blood pressure, and increased risk of heart disease, stroke, and diabetes. Luckily, positive air pressure therapy is very effective in treating obstructive sleep apnea.

Kleine-Levin syndrome is a rare disorder that mostly affects teenage males, and it’s characterized by the behavioral changes such as an increased sex drive, the need for excessive amounts of sleep (over 20 hours a day), and overeating. When awake, affected people seem very disoriented, show irritability, lack of emotions and energy, and may experience hallucinations. These episodes last for days or weeks, and then a person goes into a few months of normal behavior. The cause of Kleine-Levin syndrome is not known, and weirdly, in most cases, the condition disappears later in life.

Excessive daytime sleepiness is a symptom of many other disorders, including hypothyroidism, depression, delayed sleep phase syndrome, periodic limb movement disorder, and many others. Brain tumors, head trauma, cerebral arteriosclerosis, psychosis, and uremia can cause symptoms that resemble those of narcolepsy.


The diagnosis of narcolepsy consists of a comprehensive clinical study that has the goal to rule out other disorders that could be a potential cause of occurring problems. Since symptoms of narcolepsy appear in many different conditions, the diagnosis is not that simple. A physician will take a close physical exam, and also talk about the patient’s medical history and symptoms. They might ask them to fill out a sleep diary for a week or two, where a person can keep track of their sleeping habits. That includes sleeping and waking times, night disruptions, daily energy levels, nap, activity, and others. This data gives doctors more perspective and can help them plan the next steps.

An overnight sleep study called polysomnography is required to determine the cause of sleep disturbances. It is done in a specialized facility where the sleep technicians measure brain waves, respiration, heart rate, body and eye movement, snoring, and muscle tension, while you are sleeping. They can also determine characteristics of REM sleep that should begin after 60 to 90 minutes after falling asleep, but with narcolepsy, it happens approximately 15 minutes from the beginning. 

A multiple sleep latency test often happens the day after the sleep study. It measures the time it takes people to fall asleep during the day. Usually, there are 4 or 5 opportunities, and people with narcolepsy appear to fall asleep more easily. Also, they will achieve REM sleep during short naps, which is something that other people don’t experience.

Cerebrospinal fluid analysis is helpful with diagnosing narcolepsy, as low levels of hypocretin in a cerebrospinal fluid almost always indicate this disorder.


Unfortunately, there is no definite cure for narcolepsy, and people affected by it go through their lives trying to manage the symptoms. Luckily, excessive daytime sleepiness and cataplexy can be both controlled with medications, and with additional lifestyle changes, symptoms became reasonably tolerable.

Medications include:

  • Modafinil. It is a central neural system stimulant, and it’s usually the initial treatment for this disorder. It is a popular choice since it has fewer side effects and it is less addictive than other stimulants. Modafinil improves alertness and reduces daytime sleepiness in the majority of people.
  • Sodium oxybate. It is also known as gamma hydroxybutyrate (GHB), and it reduces cataplexy and daytime sleepiness. Since it is a strong sedative that is taken twice a day, the distribution of GHB is strictly controlled.
  • Amphetamine-like stimulants. These drugs are usually prescribed to treat excessive daytime sleepiness when Modafinil doesn’t prove useful. They come with more side effects such as irritability, shakiness, heart rhythm disturbances, sleep disruptions, and because of that, they need to be closely monitored. People taking these stimulants should always be careful since the amphetamine is risky for potential abuse.
  • Antidepressants. They are usually used to treat cataplexy, sleep paralysis, and hallucinations. Two main classes of antidepressants are used: tricyclics and selective serotonin and noradrenergic reuptake inhibitors. These drugs produce fewer side effects than amphetamines, but some may include impotence, heart rhythm irregularities, and high blood pressure.

Lifestyle Changes

Medication treatment works for most of the patients, but it is always recommended to combine with certain changes in life habits. These strategies can help manage occurring symptoms:

  • Taking scheduled short naps when you feel the sleepiest. It should prevent sudden sleep attacks from happening and increase energy and alertness during wake hours.
  • Maintaining a regular sleep schedule. Going to bed and waking up at the same time every day can help people sleep better. Even if you get the urge to sleep in on the weekends, try to fight it.
  • Creating a relaxing bedtime routine. It helps to calm down before going to bed, and it can help people fall asleep faster. You can try reading a book, taking a hot bath, meditating, breathing exercises, or listening to relaxing music. Also, make sure to remove any distractions from your bedroom. Keep it dark and cold to minimize nighttime arousals and sleep fragmentation.
  • Exercising daily. A short 20 minutes of moderate exercise can help you sleep better and avoid gaining excess weight. Be sure to do it at least 4 hours before going to bed, as exercising later can be counterproductive, and leave you unable to fall asleep.
  • Eating a balanced diet and avoiding large meals before bed. Also, people shouldn’t drink alcohol and caffeine at least 6 hours before bedtime and should avoid smoking altogether.

Safety precautions are essential for people with narcolepsy, especially when driving. Taking medication regularly and following other guidelines that a medical professional prescribed is vital, and minimizes chances of accidents. 

A person’s mental health can suffer when they have troubles maintaining work, intimate, and social relationships. People not familiar with this condition can find sleep attacks humorous, or see them as a sign of laziness, which can negatively affect people suffering from it. That is why the Americans with Disabilities Act require employers and schools to adjust the schedule to the affected person. They might be able to take scheduled naps and perform more demanding tasks when they are most alert. Educating others about narcolepsy is also useful so that these people don’t feel embarrassed or discluded. Additionally, numerous support groups offer emotional support and practical advice to help individuals cope with this disorder.

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