What is narcolepsy?


What is narcolepsy?

Narcolepsy is a neurological (nervous system) disorder that affects the control of sleep and wakefulness. People with narcolepsy experience a great deal of daytime sleepiness and uncontrollable episodes of falling asleep during the daytime, even though they have had enough sleep. These sudden sleep “attacks” may occur during any type of activity and at any time of the day.

Who gets narcolepsy?

Approximately 1 in 2,000 Americans has narcolepsy. The risk of developing narcolepsy is greater in first-degree relatives (i.e., parents, siblings, offspring) of narcoleptics (people who have narcolepsy). Narcolepsy can occur in people of all ages, but the first sign of daytime sleepiness usually appears in the teenage years or twenties. In many cases, narcolepsy is not diagnosed, and therefore, is not treated.

What causes narcolepsy?

Scientists have discovered that animals and humans with narcolepsy have a loss of a neuropeptide (chemical signal) in the brain called hypocretin. Hypocretin is important for stabilizing wake and rapid eye movement (REM) sleep states. A shortage causes excessive sleepiness, and features of REM sleep (also called “dreaming sleep”) become present during wakefulness.

What are the symptoms of narcolepsy?

Symptoms of narcolepsy include:

  • Excessive daytime sleepiness (EDS) — Almost all patients with narcolepsy have this symptom. In general, EDS interferes with normal activities (work, school, etc.) every day, whether or not patients get enough sleep at night. People with EDS report mental cloudiness, a lack of energy and concentration, memory lapses, a depressed mood, or extreme exhaustion.
  • Cataplexy — This symptom consists of a sudden loss of muscle tone that leads to feelings of weakness and a lack of voluntary muscle control. The muscle tone is lost as a result of strong emotions, such as laughter, joking, surprise, or anger. Attacks can occur at any time the person is awake. The attacks range from a brief buckling of the knees or slackness in the jaw to total paralysis with collapse. Cataplexy usually lasts a few seconds to several minutes. The rate of attacks ranges from a few in a lifetime to several per day. Cataplexy occurs in at least 60% of people with narcolepsy.
  • Disrupted nighttime sleep — This symptom occurs in 60% to 90% of patients. Awakenings may be frequent but are generally brief, and the patient is often unaware that they have taken place.
  • Sleep paralysis — This symptom, which affects approximately 60% of narcoleptics, involves the temporary inability to move or speak while falling asleep or waking up. There is often a feeling of being unable to breathe, which can be frightening. Episodes of sleep paralysis usually go away in a few minutes.
  • Hallucinations — Usually, these delusional experiences are vivid and may be frightening. The hallucinations occur when the person falls asleep, or wakes up. Hallucinations can be visual (seen), tactile (felt), or auditory (heard). Examples include seeing a person or animal in the room, feelings of levitation (floating) or sensations of being touched, and hearing an alarm or voices. These types of hallucinations occur in approximately 60% of narcoleptic patients. The hallucinations are called “hypnagogic hallucinations” when they occur while the person is falling asleep, and “hypnopompic hallucinations” when they happen during awakening.