Narcolepsy: Symptoms & Signs

Medically Reviewed on 10/21/2021

Narcolepsy is a chronic disease of the brain that causes excessive sleepiness during the daytime. Narcolepsy usually begins in teenagers or young adults.

Signs and symptoms of narcolepsy include excessive daytime sleepiness, loss of muscle tone, abnormalities in perception (referred to as hypnagogic hallucinations), and sleep paralysis (an inability to move or talk). Other associated symptoms can include disturbed sleep at night, blurred vision, frequent awakening at night, carrying out actions without conscious awareness (automatic behavior) when transitioning from wakefulness to sleep.

Causes of narcolepsy

While the cause of narcolepsy is not fully understood, abnormalities in the structure and function of a group of nerve cells in the brain known as hypocretin neurons seem to play a role in its development.

Other narcolepsy symptoms and signs

  • Abnormalities in Perception (Hypnagogic Hallucinations)
  • Blurred Vision
  • Disturbed Sleep at Night
  • Excessive Daytime Sleepiness
  • Frequent Night Awakenings
  • Loss of Muscle Tone
  • Sleep Paralysis


Why do we sleep? See Answer

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Jameson, J. Larry, et al. Harrison's Principles of Internal Medicine, 20th Ed. New York: McGraw-Hill Education, 2018.