Narcolepsy is a relatively rare sleep disorder that causes a person to feel sleepy or fall asleep suddenly during the daytime hours.

Between 135,000 and 200,000 people in the United States have narcolepsy. This neurological condition is difficult to diagnose because it shares features with other disorders. Researchers believe narcolepsy may be underdiagnosed.

This article will look at the symptoms you might experience with narcolepsy, what conditions it’s similar to, and how it’s diagnosed and treated.

The true prevalence of narcolepsy isn’t known and may vary from region to region. Researchers suspect the condition is underdiagnosed or sometimes misdiagnosed as other medical conditions.

Conditions that may be either confused or comorbid (occurring together) with narcolepsy include:

The National Organization for Rare Disorders reports that around 1 in every 2,000 people may have narcolepsy. Other researchers estimate that approximately 20 to 55 per 100,000 people worldwide may live with the condition.

In some countries, this number may be higher or lower. Some researchers point to a “striking” gap in data between reporting of Caucasian and European cases versus those in other populations.

Do you nod off at random points throughout the day? Do you also have trouble sleeping through the night?

If you suspect you have narcolepsy, you may experience the following symptoms:

  • Daytime sleepiness. Excessive daytime sleepiness (EDS) is the kind of sleepiness that causes someone to fall asleep frequently when they don’t want to — at the wrong time and place. People may also experience sleep attacks.
  • REM sleep changes. REM is a state of sleep during which the eyes move rapidly. People with narcolepsy may quickly slip into REM sleep cycles even during the day.
  • Sleep paralysis. As a person awakens from REM sleep, there may be a few seconds to minutes when they’re unable to speak or move their body. Some people with narcolepsy have this symptom frequently, some not at all.
  • Hallucinations. Some people may experience vivid and sometimes disturbing dream-like images either when falling asleep or waking up. Usually, hallucinations are visual, but they may also involve touch, smell, and other senses.
  • Cataplexy. This symptom, which not all people with narcolepsy experience, involves a sudden loss of muscle tone. This may be subtle, with the loss of some of the muscle tone in the the face or hand, or it may affect many muscle groups and result in the person falling to the ground. Unlike sleep paralysis, cataplexy happens when a person is fully awake. It’s often triggered by strong emotions (laughter, anger, fear, excitement, etc.).
  • Nighttime sleep disruption. People with narcolepsy may also have trouble falling and staying asleep at night. They may experience vivid dreams, sleep apnea, insomnia, or movements while sleeping, such as acting out and leg movements.
  • Automatic behavior. If sleep episodes are very brief, people may continue doing habitual activities, such as brushing teeth or driving. They may also put things in drawers where they don’t belong and write illegibly.

The symptoms of narcolepsy can overlap with other conditions. For example, a person may have excessive daytime sleepiness if they’ve had a head injury or are taking certain medications.

Cataplexy may also sometimes be confused with drop attacks or seizures from epilepsy.

A person can have one of several forms of narcolepsy:

  • with cataplexy (narcolepsy type 1)
  • without cataplexy (narcolepsy type 2)
  • as a result of a brain injury, or lesion in the brain (secondary narcolepsy)

With cataplexy, a person experiences muscle weakness, particularly in response to strong emotions. This means their body or parts of the body may go limp without warning. They may lose control of their muscles or be unable to move during episodes that last anywhere between a few seconds and 2 minutes.

People with cataplexy have low levels of a brain chemical called hypocretin. It’s this marker that can help with diagnosis, as cataplexy is not a feature of similar disorders.

Scientists estimate that somewhere between 25 and 50 in 100,000 people have narcolepsy with cataplexy, according to a 2007 study.

Researchers continue to work on learning the cause of narcolepsy.

Currently, many researchers believe that the following causes are possible:

  • Low hypocretin levels. People who have narcolepsy with cataplexy may have very low levels of this chemical. People who have narcolepsy without cataplexy generally have normal levels.
  • Autoimmune disorders. If you have an autoimmune disorder, your immune system may attack healthy parts of your body (cells, tissues, etc.). This may affect how much hypocretin your body produces.
  • Family history. If other people in your family have narcolepsy, there’s a higher chance you may, too. That said, most cases of narcolepsy are “sporadic” (occurring at random).
  • Brain injury or issue. In rare cases, a brain injury may lead to narcolepsy. After an injury, the part of the brain that regulates REM sleep may not function normally. This may also be the case if you have a brain tumor or other issue.
  • Other triggers. Other possible triggers may include psychological stress and certain infections.

It may take up to 10 years after symptoms appear to get a confirmed diagnosis of narcolepsy.

Researchers suggest that symptoms may start between the ages of 7 and 25 on average. Symptoms may start out mild but become more noticeable with age. Eventually the symptoms are stable over many years.

At your appointment, a doctor will ask about your your sleep symptoms, medical history or family history. From there, you may be asked to do the following:

  • Log your symptoms. The doctor may ask you to keep a log of daytime and nighttime sleep. It’s important to note cataplexy because it’s a specific symptom of narcolepsy.
  • Have an overnight sleep study. Also called a polysomnography (PSG), a sleep study is usually performed in a lab setting. The doctor will monitor your breathing, brain, and muscle activity as well as your REM sleep patterns to rule out other conditions like sleep apnea or movement disorders. People with narcolepsy may enter REM sleep in less than 15 minutes.
  • Have a multiple sleep latency test (MSLT). An MSLT measures how quickly you can fall asleep during the day and enter a REM cycle. Unlike during a sleep study, where you’re asked to sleep normally through the night, in an MSLT you’re asked to take short naps a couple of hours apart (4 to 5 times) during the day. Falling into REM within 15 minutes in at least two of the five naps is a marker for narcolepsy.
  • Try other tests. The doctor can also test your spinal fluid for the presence of hypocretin. The fluid (cerebrospinal fluid or CSF) is obtained through a spinal tap.

Narcolepsy is a lifelong condition. Treatments can help with the symptoms, but there’s currently no cure.

Treatments include:

  • Wake-promoting agents. Modafinil or armodafinil promote wakefulness and alertness. Methylphenidate is an amphetamine-like stimulant that also promotes wakefulness, but may have more side effects and addictive properties. More recently, pitolisant (Wakix) and solriamfetol (Sunosi) have been introduced.
  • Antidepressants. Tricyclic antidepressants (TCAs) or serotonin-norepinephrine reuptake inhibitors (SNRIs) may help control episodes of cataplexy.
  • Sedatives. Sodium oxybate (gamma hydroxybutyrate or GHB) can be taken at night to help with both cataplexy and daytime sleepiness.

Lifestyle modifications, such as practicing good sleep hygiene habits and taking brief scheduled naps (e.g. after lunch or later in the afternoon), are other options. Exercising each day and avoiding caffeine, alcohol, and nicotine may also make nighttime sleep more restful and help with daytime sleepiness.

You may also ask a doctor about local support groups for people with narcolepsy. Online support is also available at places like the Narcolepsy Network or Rare Connect’s Narcolepsy Community.

While narcolepsy is rare, it’s also difficult to diagnose. The sooner you seek a diagnosis, the sooner you may find help for whatever sleep issue you’re experiencing.

If you do have narcolepsy, a doctor can help you find the appropriate treatments and lifestyle modifications to live your best life.