Caffeine, the world’s most widely used psychoactive substance, attracts a lot of research. PubMed contains 23,000+ citations for caffeine, for instance.Caffeine also attracts controversy. Some scientists argue that caffeine is a benign and useful drug whose side effects are only of concern in regard to a small number of “sensitives”, including those with pre-existing anxiety or similar symptoms. They note that caffeine improves attention, reaction time, numeric and verbal memory, and work output and endurance in long-term exercise.
But other researchers claim that caffeine causes multiple damaging effects ranging from boosting blood pressure to disrupting sleep, and that these affect hundreds of millions. Continue reading »