Most everyone knows the feeling—headache, drowsy, trouble concentrating. Maybe you are irritable, anxious, or have suddenly become very clumsy—all simply because you missed your morning dose of caffeine. It is estimated that in North America between 80 to 90 percent of the adults and children consume caffeine daily.  Caffeine is the most commonly used mood-altering drug in the world.  According to the website of the Johns Hopkins Bayview Medical Center, “in the United States the average per capita daily intake among adult caffeine consumers is 280 milligrams (the equivalent of...