Caffeine is a natural stimulant most commonly found in coffee, tea, cocoa, and some plants, known for its ability to increase alertness and reduce feelings of tiredness. It works by blocking adenosine, a chemical in the brain that promotes sleep, which helps sharpen focus and improve reaction time. When consumed in moderation, caffeine can enhance mood and mental performance, but excessive intake may lead to restlessness, sleep problems, or jitteriness.
