Following a period of overnight deprivation, 58 smokers participated in a 90-min laboratory assessment in which they viewed a non-stressful movie and smoked two 0.5-mg nicotine-containing cigarettes. The first cigarette was given to all subjects following 25 min of adaptation and baseline. The next cigarette was provided at their request, which occurred 9-12 min later. "Heavy" and "light" smokers were grouped according to their average morning cotinine values, which fell above or below 250 ng/ml, respectively. The results showed that, relative to their baseline, heavy and light smokers experienced about the same level of post-smoking change in blood nicotine, heart rate and blood pressure. However, heavy smokers showed a significantly greater delta from baseline in post-smoking measures of epinephrine, norepinephrine, tension reduction and increase in vigor enhancement. A strong and consistent correlation was observed between post-smoking increases in epinephrine, tension reduction and increased vigor.