Hormonal and subjective effects of smoking the first five cigarettes of the day: a comparison in males and females.

The effects of smoking normal-nicotine-delivery cigarettes on serum cortisol, plasma beta-endorphin (BE), and mood were measured in 8 male and 8 female smokers; 8 male and 8 female nonsmokers served as sham-smoking controls. Smoking five cigarettes of the smokers' usual type after overnight deprivation, either ad lib or via a quantified smoke delivery system, produced small but reliable elevations in serum cortisol concentrations; BE was elevated somewhat after two, but not after four or five cigarettes. Smoking-induced elevations in serum cortisol were correlated with decreases in self-reported drowsiness after two and five cigarettes. Additionally, female smokers reported more drowsiness at baseline and after smoking nicotine-free cigarettes than did male smokers or female nonsmokers. Results suggest that smoking-induced elevations in serum cortisol, which persist for at least the first five cigarettes of the day, may modulate the arousing effects of smoking under conditions of low arousal. Also, nicotine-deprived female smokers may experience subnormal arousal compared to male smokers or female nonsmokers.