In addition, as a type of mental stimulant, caffeine increases alertness, memory, and reaction speed. 5. (6 Because it fights tiredness it improves performance on tasks like driving, flying, and solving simple math Ot 5 problems. It is true that caffeine can increase blood pressure, but the effect is usually temporary and therefore not likely to cause heart trouble, especially (thus) if caffeine is consumed in sensible amounts. 8 Caffeine's effects are real, but most often mild. 10 This is why many of the most popular drinks on earth contain caffeine.