Causes

Smoking has both biological and behavioral components. In the early days, smoking was thought mostly to be habit forming, not addictive, due to social situations or the rituals of lighting up. The key to quitting, the theory said, was to change your behavior - such as finding something different to do with your hands or not being around other smokers.

Today, we understand the biology of nicotine addiction. Researchers have discovered that nicotine is a powerfully addictive drug, which takes about 10 to 12 seconds to get from the lungs into the bloodstream and brain. For some people, it can be as addictive as heroin or cocaine.

People smoke for a variety of reasons. Young people smoke to look mature, to be like their friends or to feel accepted. Adults often smoke because they are under stress. Smoking can help them relax or give them energy when they feel overwhelmed. Others smoke to help control their weight - the decreased sense of taste and smell acts as an appetite suppressant. Finally, some people just enjoy smoking. Many people who quit miss the habit and what it did for them.

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This article was reviewed and updated June 2007.