Caffeine occurs naturally in over 60 different types of plants. It is also produced artificially and added to certain foods.

For Americans, coffee is the biggest source of caffeine, and it's easy to see why. The delicious aroma, rich taste, and good buzz of a cup of coffee is hard to beat. It’s one of life’s simple pleasures that people everywhere take advantage of. Coffee is also an important social centerpiece in American life. Can you imagine a school, church, or community function without the security of a hot beverage in hand?

While most people still get their caffeine in the traditional form of a pot of coffee or a cup of tea (or in what’s become another traditional form – a bottle of Coke), energy drinks can also be a source of caffeine. Guarana is an active ingredient in many of these energy drinks, 4 grams of which contains about 160 mg of caffeine. That’s twice the amount of caffeine in a normal cup of instant coffee.

Caffeine is also found in chocolate, and in pain relievers and over-the-counter tablets such as No-Doz and Vivarin.

Caffeine affects different people in different ways. The amount of caffeine you have, your age, any medications you are taking, any alcohol you drink, the time of day you get your caffeine, your mood, your level of tiredness, and how sensitive your body is in general, all make a difference to how caffeine affects you.

• “Wake-up call,” “energy-boost,” and “pick-me-up” are among the most quoted physical benefits of caffeine. Some studies have even shown that caffeine can increase memory, powers of reasoning, motor skills and reaction times. (However, improved performance with caffeine can also be considered an effect of addiction!).
  
  
• Sleep disturbance is one of the more negative effects of caffeine consumption. Some people find that as little as one cup of coffee can interfere with their sleeping patterns. However, if you stop caffeine consumption at least five hours before sleeping, the effects should be minimal.
  
  
• Other negative effects of caffeine include the loss of calcium and potassium, which causes sore muscles and delayed recovery after exercise.
  
  
• Among the less well-known effects of caffeine are that it raises body temperature and makes your digestive system produce more acid. Polyphenols in coffee and tea can interfere with iron absorption, so it you're at risk for anemia it’s best to drink caffeinated beverages an hour before a meal, rather than afterward.
  
  
• Caffeine is a also diuretic, so it dehydrates your body and causes you go to the bathroom more often.