A synthetic central nervous system stimulant with wakefulness-promoting activity. Modafinil appears to inhibit dopamine reuptake, resulting in an increase in extracellular dopamine. This agent exhibits pronounced wakefulness-promoting activity (without sympathomimetic activity) and may improve cognitive function in certain clinical settings. or A drug that is being studied as a treatment for fatigue in patients with cancer. It belongs to the family of drugs called stimulants.