Provigil, the brand name for the medication modafinil, is a prescription central nervous system stimulant primarily used to promote wakefulness in adults suffering from excessive daytime sleepiness. It is FDA-approved for the treatment of narcolepsy, obstructive sleep apnea, and shift work sleep disorder. Unlike traditional stimulants, Provigil is classified as a "eugeroic" or wakefulness-promoting agent, as it works by altering specific neurotransmitters in the brain—such as dopamine—to improve alertness without the intense "jittery" effects often associated with amphetamines. While generally well-tolerated, common side effects include headache, nausea, and nervousness. Because it carries a lower risk for addiction than other stimulants, it is often a preferred choice for long-term management of sleep-related disorders.