Provigil is a medication that treats excessive tiredness caused by certain sleep conditions like narcolepsy, sleep apnea and shift work sleep disorder. For obstructive sleep , take this medication by mouth with or without food as directed by your doctor, usually once daily in the morning.If you are using modafinil for shift work sleep disorder, take it by mouth with or without food as directed by your doctor, usually once a day.If in case facing any problem try to ask your doctor.