Early records suggest that the Chinese were brewing tea 5,000 years ago. In Africa highly valued coffee beans were once used as currency. In the New World, Aztec royalty were served special chocolate drinks. Caffeine is a naturally occurring substance in certain plant parts, including coffee and cocoa beans, tea leaves, and kola nuts. We consume caffeine mostly from coffee, tea, chocolate, and soft drinks.
Caffeine acts as a mild stimulant to the central nervous system.
People have long used coffee for just that reason - to keep alert and prevent fatigue. Caffeine may also temporarily speed the heart rate. But these physical effects wear off after a few hours. Over the years studies have explored the connection between caffeine and health. And no studies have shown that caffeine causes attention deficit disorder in children.