Uses Modafinil reduces extreme sleepiness due to narcolepsy and other sleep disorders, such as periods of stopped breathing during sleep (obstructive sleep apnea). It is also used to help you stay awake during work hours if you have a work schedule that prevents you from having a normal sleep routine (shift sleep disorder). This medicine does not cure these sleep disorders and cannot get rid of all your sleepiness. Modafinil does not take the place of sleep enough. It should not be used to treat tiredness or stop sleep in people who do not have a sleep disorder. It is not known how modafinil works to keep you awake. It is thought to work by affecting certain substances in the brain that control the sleep/wake cycle. How to use Provigil Read the Medication Guide provided by your pharmacist before you start using modafinil and each time you refill a medication. If you have any questions, ask your doctor or pharmacist. For narcolepsy, take this medication by mouth with or without food as directed by your doctor, usually once daily in the morning. Or, if directed by your doctor, the total daily dose of Modafinil can be divided into a morning dose and a midday dose. For obstructive sleep apnea, take this medication by mouth with or without food as directed by your doctor, usually once daily in the morning. Continue your other treatment (such as CPAP machine, oral device) unless your doctor tells you to stop.