Armodafinil is a medication used to improve wakefulness in adults with excessive sleepiness caused by narcolepsy, obstructive sleep apnea, or shift work sleep disorder. It is a type of stimulant that works by increasing the activity of certain chemicals in the brain that helps to promote wakefulness and alertness. Armodafinil is sold under the brand name Nuvigil. It is available by prescription only and should be used only under the supervision of a healthcare provider.