Daytime sleepiness due to a problem called narcolepsy can be treated with the correct use of Modvigil. It keeps people vigilant during odd working hours, especially if they have a work schedule that prevents them from getting routine slumber. This pill impacts the functioning of certain chemicals in the brain that controls the circadian rhythm. Individuals allergic to Modvigil or any of its ingredients must share their medical history with their doctor before its use.