1 OPINION. 2  The screening process for Syrian refugees is much more rigorous than for other visitors coming to the U.S. (AP Photo/Hassan Ammar)
About 250 milligrams of caffeine â or the equivalent of 2 to 2 1/2 cups (473 to 591 milliliters) of plain, brewed coffee â a day may cause this effect. If you have type 2 diabetes and you're struggling to control your blood sugar levels, limiting the amount of caffeine in your diet may provide a benefit.
In particular, caffeine targets the cerebral cortex and the brain stem in the central nervous systems. Doses of 100-200 mg result in increased alertness and wakefulness, faster and clearer flow of thought, increased focus, and better general body coordination. It also results in restlessness, a loss of fine motor control, headaches, and dizziness.