is a very effective, inexpensive way to boost alertness. It is a natural stimulant. Second only to water, caffeinated beverages are one of the most commonly consumed fluids in the world. Coffee, tea, hot chocolate, and soda are popular options. Caffeine can also be found in certain foods, such as chocolate. Excessive use of caffeine may rarely have adverse consequences
, such as a rapid heart rate, nervousness, or a withdrawal headache.