Smoking cessation leads to reduced stress, but why?

Recent longitudinal studies have demonstrated that smoking cessation leads to reduced feelings of stress. This finding is not predicted by either of the two main models for smoking behavior. The nicotine resource model (Warburton) states that nicotine is used to cope with external stressors, and predicts that smokers will suffer from increased stress when they quit smoking. The deprivation reversal model (Schachter), suggests that smoking reverses the deleterious effects of deprivation; cessation will then lead to a period of increased stress, followed by a return to baseline. Although the stress/cessation data agree with neither model, they are consistent with a third explanation, namely that smoking causes stress. This model states that acute nicotine deprivation (i.e., between cigarettes) leads to increased stress. Smokers then use cigarettes to reverse these withdrawal effects and "normalize" their mood. This model explains some paradoxical aspects of the smoking/mood relationship. First, why smokers are calmed by smoking, yet report high average levels of stress. Second, why stress levels become reduced after smoking cessation; this is because the former smoker no longer suffers from the adverse mood effects of acute nicotine depletion.