Caffeine is the fruit commonly known for its ability to keep you awake, particularly due to its stimulating effects on the central nervous system. Found naturally in various plants, caffeine is most notably associated with coffee beans, tea leaves, and cacao pods. When consumed, caffeine blocks adenosine receptors in the brain, which helps to reduce the feeling of tiredness and increase alertness. This is why many people consume caffeinated beverages to boost energy levels and improve focus, especially during long work hours or late-night activities. However, excessive intake can lead to side effects like restlessness and insomnia.