Whether you’re a student in need of a late-night pick-me-up before an exam or a hardworking adult pulling an early morning shift, you may depend on caffeine to keep you alert. A study in the Journal of the American Dietetic Association reports that Americans consume an average of 200 milligrams of caffeine daily. Most of this is from coffee and sodas, and a growing source of caffeine in the diet comes from energy drinks.
