Modafin is used to promote wakefulness in patients with excessive sleepiness associated with narcolepsy, obstructive sleep apnea (in addition to treatment of the underlying obstruction) and shift work sleep disorder. Narcolepsy is a chronic disease of the brain and spinal cord characterized most commonly by a recurrent, uncontrollable desire to sleep. Shift work sleep disorder is a condition in which the normal rhythm of sleep is disturbed, often as a result of working at night. Sleep apnea is a condition where sleep is constantly interrupted at night because of pauses in breathing or shallow breathing usually due to obstruction of the upper airway.

The recommended dose is 200 mg once daily not to exceed 400 mg. Modafin should be administered in the morning for treating narcolepsy or obstructive sleep apnea, and one hour prior to work in those with shift work disorder. Modafin can be taken with or without food. The 400 mg dose may not be more effective than the 200 mg dose.

The most common side effects of Modafin are headache, upper respiratory tract infection, nausea, nervousness, anxiety, and insomnia. Modafinil also may cause serious skin reactions, multiple organ hypersensitivity reactions, high blood pressure, fainting, psychosis, thoughts of suicide, and abnormal heart beats.