Questions & Answers: What are caffeine's effects?
Q. What are caffeine's psychological benefits and risks?
A. Caffeine is the most widely used psychoactive drug in the world. Up to 90% of Americans take it regularly, usually in the form of coffee, tea, or soft drinks, sometimes in a tablet (No-Doz and others). The average daily dose, 300 mg, is the equivalent of three cups of coffee. No wonder selling expensive caffeinated drinks is good business!
The best way to determine the risks and benefits of a drug is to give the drug or a placebo to matched groups of people who have never been exposed to the drug before. But it's hard to find people who don't use caffeine, and the small minority who don't may abstain because they are physiologically different from others, finding caffeine unpleasant rather than pleasurable. Another problem is that most controlled studies don't last long enough to reveal the effects of chronic use. Researchers are more interested in habitual users.