Beginning of Essay
Caffeine is the most widely used drug in the world. It is an effective stimulant of the central nervous system and in large amounts can produce undesirable side effects such as: nervousness, insomnia, rapid and irregular heartbeats, elevated blood sugar and choles ....

Middle of Essay
.... among some users, but its impact on creativity and other intellectual activities is hard to define. Caffeine can be habit-forming. Some regular users who give it up may experience withdrawal symptoms twelve to sixteen hours after the last dose, such as: drowsiness, headaches, lethargy, irritability, disinterest in work, depression, occasional nausea and vomiting. How caffeine affects you depends on what and how much you drink. Strongly brewed coffee or tea has much more caffeine than a weakly brewed drink. Age and size make a difference too: A caffeinated soft drink consumed by a child can have the same effect as four cups of coffee for an adu ....