• Millions of Americans drink coffee, which is rich in caffeine.coffee in coffee image by Maria Brzostowska from Fotolia.com
  
  Caffeine use can have side effects that consumers need to know. Consumed by an estimated 85 percent of adults in the U.S., caffeine is a stimulant present in coffee, tea and other drinks such as sodas. Although caffeine is not usually harmful, when consumed in large amounts over long periods of time, caffeine can have long-lasting effects on the body.
  
  

Insomnia

• Caffeine is widely used as a means of staying awake. Unsurprisingly, this can lead to insomnia. Caffeine stimulates the brain, making it difficult to settle into sleep. Caffeine-induced insomnia may only last a few nights, but it can become a persistent problem, especially if caffeine is taken daily in any form. If caffeine becomes a serious impediment to a good night's sleep, try to gradually eliminate caffeine from your diet.
  
  

Heart Disease

• Caffeine use causes noticeably faster heartbeats called heart palpitations. While these can be unpleasant, they are not considered dangerous in most cases. However, caffeine can also raise blood pressure, which may increase the risk of heart attack or stroke. While moderate caffeine use may not be harmful to healthy adults, people with heart disease or high blood pressure should reduce or halt their caffeine intake.
  
  

Memory

• While some feel that caffeine helps concentration and memory, this may not be the case. A 2008 study showed that caffeine interferes with the brain's ability to recall details. In the study, placebos were more effective in helping people recall details, showing that any cognitive advantage caffeine seems to provide is attributable to people's expectations, rather than reality.
  
  

Addiction and Withdrawal

• Caffeine is an addictive substance. After long-term daily caffeine use, a person may require caffeine to function. If a person who has become addicted to caffeine stops consuming caffeine abruptly, she may experience caffeine withdrawal. Symptoms of withdrawal include headache, fatigue and flu-like symptoms such as muscle pain and nausea. Withdrawal makes quitting caffeine difficult, which is why it is best to gradually reduce caffeine intake.