Explaining link between emotion and addictive substance use

What drives a person to smoke cigarettes? What role do emotions play in this addictive behavior? Why do some smokers puff more often and more deeply or relapse many years after they've quit? If policy makers had those answers, how could they strengthen the fight against the global smoking epidemic? A new report by researchers offers a key insight: sadness plays an especially strong role in triggering addictive behavior relative to other negative emotions like disgust.