Effects of smoking on diurnal variations of subjective activation and mood

This study assessed the influence of smoking on diurnal variations in subje ctive activation and mood, with no restrictions placed on subjects' usual s moking habits after the first cigarette of the day. Forty-two students (21 smokers and 21 non-smokers) responded to questions on unipolar visual analo gue scales every hour from 08:00 to 21:00 hours. At 08:00 h, the smokers we re in a situation of nicotine deprivation. Each visual analogue scale was a nalyzed independently to determine whether they differ in sensitivity to ti me of day. We confirmed that subjective activation and mood improved after subjects smoked their first morning cigarette, with vigour, sleepiness and sadness being the most sensitive scales. Smokers' diurnal functions on nega tive scales of activation varied within a wider range than did non-smokers' and optimal moments were delayed 3 h as a result of worse morning ratings and greater post-lunch interference. The only mood scale sensitive to smoki ng was happiness, with smokers having a lower mean score than non-smokers, and a delay of 6 h in peak: ratings. These results support reports of diffe rences in the circadian rhythmicity of smokers and non-smokers, even when t he former smoke at will. Smokers' presentation of suboptimal levels of acti vation and mood at critical diurnal periods is consistent with models of de privation-reversal and acute nicotine depletion over the course of the day. Copyright (C) 2000 John Wiley & Sons, Ltd.