: Most people Buy Provigil Online is used to treat excessive sleepiness.It is used to treat excessive sleepiness caused by sleep apnea, narcolepsy, or shift work sleep disorder. It is thought to work by altering the natural chemicals (neurotransmitters) in the brain. Provigil tablets come in the following strengths: i.e 100 mg & 200 mg. For relief of excessive sleepiness due to shift work sleep disorder, the recommended dosage is 200 mg per day.Provigil is sometimes prescribed off-label to treat ADHD. (With off-label use, doctors prescribe a drug for a purpose other than what it’s approved for.)