Tea contains caffeine which, when taken in the proper quantity, simulates every organ in the body.
It has a particularly strong effect on the central nervous system, heart and liver. This reaction is even more pronounced when one is sleepy or tired. A cup of tea or coffee will help clear a dull mind after rising in the morning or after a prolonged period without sleep. The power to stimulate and awaken the mind comes from caffeine. It is also said that the amount of caffeine contained in normal servings of green tea can stimulate the skeletal muscles and facilitate muscular contraction.