Caffeine may be the most widely used stimulant in the world. It is found in a variety of plants, dietary sources (including coffee, tea, chocolate, cocoa, and colas), and non-prescription medications. The average caffeine consumption in the USA is approximately 2 cups of coffee per day (200 mg); 10% of the population ingests more than 1000 mg per day. Caffeine is a socially acceptable, legal drug con-sumed by all groups in society.