One good thing about caffeine is that it is a central nervous system stimulant - increases your metabolic rate, which helps burn more calories (although exercise is still more effective). Also it temporarily increases mental clarity, as well as muscular coordination. If you are a person with breathing problems, caffeine can open up air passages and help to increase respiration rates. If you have low blood pressure, caffeine can also give it a modest boost. Overall, a dosage of 50 to 100mg of caffeine can have a stimulating effect on your system and increase your daily functions in life.