The Caffeine High
Caffeine is the most popular and widely consumed drug in the world. It is in coffee, tea, soft drinks, chocolate, and medications, including cold pills. Caffeine is the only drug in the food supply, and like all drugs, it causes an array of physiological changes.
As a stimulant, caffeine has a direct effect on the brain and the central nervous system. It can ward off drowsiness, improve alertness, and speed reaction times in people who are tired and increase the muscles’ capacity for work. It can also lead to nervousness, anxiety, jitteriness, and loss of sleep.
Like other stimulants, caffeine is addictive. People develop a tolerance for it and need more to get through the day. According to researchers at the Center for Science in the Public Interest, coffee drinkers tend to become dependent on caffeine at daily doses of about 31/2 cups of coffee. As with other drug-related dependencies, caffeine produces withdrawal symptoms when regular users stop drinking coffee. These symptoms include lethargy, irritability, nervousness, and severe headaches.
Some people can consume large amounts of caffeine without noticing any effect. Others become jittery after one cup of coffee or a can of cola. Similarly, people differ in the duration of caffeine’s effect. Caffeine has a half-life of three to seven hours for the typical non-smoking adult. This means that half its effects wear off in that time. For reasons not fully understood, the half-life is shorter for smokers and longer for pregnant women.
Most experts agree that two cups of coffee a day pose little or no health hazard to adults. But the scientific evidence about high use is unclear. Some animal studies have implicated caffeine in birth defects, heart disease, and cancer. Even without conclusive evidence, the Food and Drug Administration recommends that women avoid or significantly reduce their intake of caffeine during pregnancy. Alternatives to caffeine include decaffeinated coffee (which is not without health hazards itself because it contains additives that may cause liver cancer in mice), herbal tea, and grain-based drinks. For those who need their daily fix of junk food, there are caffeine-free sodas and chocolates.