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For further information, see CMDT Part 25-15: Sleep-Wake Disorders

Key Features

  • A disorder of excessive sleepiness, manifesting in "sleep attacks"

  • Disorder begins in early adult life

  • Affects both sexes equally

  • Severity levels off at ~30 years of age

Clinical Findings

  • Tetrad of symptoms

    • Sudden, brief (~15 min) sleep attacks during any type of activity

    • Cataplexy, a loss of specific or generalized muscle tone

    • Sleep paralysis: a flaccidity of muscles with full consciousness while falling or waking from sleep

    • Visual or auditory hypnagogic hallucinations, preceding sleep or occurring during a sleep attack


  • Sleep study

    • Attacks are characterized by abrupt transition into REM sleep, a necessary criterion for diagnosis


  • Dextroamphetamine sulfate, 10 mg orally each morning, with increased dosage as necessary

  • Modafinil, 200–400 mg orally each morning or armodafinil, 150–250 mg orally each morning

    • Mechanism of action is unknown, but risk of abuse is thought to be lower than with stimulants

    • Modafinil may reduce the efficacy of cyclosporine, oral contraceptives, and other medications by inducing their hepatic metabolism

    • Common side effects include headache and anxiety

  • Imipramine, 75–100 mg orally once daily, is effective in treatment of cataplexy but not narcolepsy

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