Provigil is a medication that is used to treat sleep disorders such as narcolepsy, obstructive sleep apnea, and shift work sleep disorder. It is also used to improve wakefulness in people with excessive daytime sleepiness associated with conditions such as ADHD. The active ingredient in Provigil is modafinil, which works by increasing the activity of certain chemicals in the brain that promote wakefulness. It is important to take Provigil exactly as prescribed by a healthcare provider and not to exceed the recommended dosage or take it for a longer period than advised. It is taken with or without food. The drugs are available in Provigil 100mg and Provigil 200mg.