Provigil is one medication used to treat narcolepsy, a condition that results in excessive sleepiness. A type of sleep disorder known as narcolepsy interferes with the brain’s ability to regulate alertness and sleep. Provigil is one medication used to treat narcolepsy, a condition that results in excessive sleepiness. A type of sleep disorder known as narcolepsy interferes with the brain’s ability to regulate alertness and sleep, which is why it makes you feel tired during the day.