The mechanism of action of Modafinil 200 mg is still not completely understood but it is thought to act by altering chemicals in the portion of the brain responsible for sleep and the circadian rhythm. It stimulates the dopamine (DA), norepinephrine (NE), and histamine (HA) neurotransmitters, which helps you remain awake and alert. Make sure to avoid consuming products that contain caffeine or other stimulants while taking Modafinil because it can significantly increase its side effects.