Narcolepsy

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

Tetrad of symptoms

• Sudden, brief 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

• 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, 10 mg orally each morning

Modafinil, 200 mg orally each morning

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

• 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 once daily orally, is effective in treatment of cataplexy but not narcolepsy