What is narcolepsy?

Narcolepsy is a neurological (nervous system) disorder that affects the brain’s ability to control sleep and wakefulness. If you have narcolepsy, you experience excessive daytime sleepiness and may have uncontrollable episodes of falling asleep during the daytime. These sudden sleep “attacks” may occur during any type of activity and at any time of the day.

Who gets narcolepsy?

Approximately one in 2,000 Americans has narcolepsy. The disorder affects males and females equally. Up to 10% of people who have narcolepsy have a relative who also has the disorder. Narcolepsy occurs in people of all ages, but the first sign of daytime sleepiness usually appears in the teenage years or twenties. Because narcolepsy symptoms mimic depression, other sleep disorders, or other illnesses, it may go undiagnosed and untreated for years.

Are there different types of narcolepsy?

Yes, there are two types of narcolepsy:

  • Type 1 narcolepsy (previously called narcolepsy with cataplexy [see symptoms section for definition]). Persons with type 1 narcolepsy have excessive daytime sleepiness plus cataplexy and/or low levels of a chemical in the brain called hypocretin.
  • Type 2 narcolepsy (previously called narcolepsy without cataplexy). Persons with type 2 narcolepsy have excessive daytime sleepiness but do not have cataplexy and have normal levels of hypocretin.

What causes narcolepsy?

Scientists have discovered that people with narcolepsy have a loss of a neurotransmitter (chemical signal) in the brain called hypocretin. Hypocretin is important for regulating the sleep/wake cycle including the rapid eye movement (REM) sleep state. A shortage of hypocretin causes excessive sleepiness, and features of REM sleep (also called “dreaming sleep”) become present during wakefulness.

Other possible factors scientists think play a role in narcolepsy include:

  • An autoimmune disorder. A person’s immune system attacks the brain cells that produce hypocretin, resulting in a shortage of this chemical.
  • Family history. Some persons with narcolepsy have close relatives with similar symptoms.
  • Brain injury or tumor. In a small number of patients, the area of brain that controls REM sleep and wakefulness can be injured by trauma, tumor or disease.
  • Infections.
  • Environmental toxins, such as pesticides, heavy metals and secondhand smoke.

What are the symptoms of narcolepsy?

Symptoms of narcolepsy include:

  • Excessive daytime sleepiness (EDS): All patients with narcolepsy have this symptom. In general, EDS interferes with normal activities (work, school, home life, social activities) every day. Although brief naps during the day may help you feel rested and alert, tiredness returns within one to two hours. People with EDS report mental cloudiness, a lack of energy and concentration, memory lapses, a depressed mood and/or extreme exhaustion.
  • Cataplexy: This symptom is a sudden loss of muscle tone or strength brought on by strong emotions, such as laughter, fear, surprise, stress or anger. Attacks can occur any time you are awake. The attacks range from a brief buckling of the knees or slackness in the jaw or drooping of eyelids to total body paralysis with collapse. Cataplexy usually lasts a few seconds to several minutes. You remain fully conscious during these attacks. The rate of attacks ranges from a few in a lifetime to several per day. Although scary, there’s no damage from these episodes.
  • Disrupted nighttime sleep: This symptom is described as frequent awakenings during the night.
  • Sleep paralysis: This symptom is the inability to move or speak just before falling asleep or just after waking up. Episodes of sleep paralysis usually go away after a few seconds to a few minutes.
  • Hallucinations: Usually, these delusional experiences are vivid and may be frightening. The hallucinations occur just before falling asleep (called hypnagogic hallucinations) or just after waking up (called hypnopompic hallucinations). Hallucinations are mainly visual (seen), but you can also feel like you can hear, taste or smell things. Examples include seeing a person or animal in the room, feelings of floating or sensations of being touched, and hearing an alarm or voices.
  • Automatic behavior: This symptom is described as falling asleep for several seconds but continues to perform routine tasks, such as eating, talking, driving or writing, without any awareness or later memory of ever doing the task.

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