Stress and Arousal Circadian Rhythms in Smokers and Non-smokers Working Day and Night Shifts

Twenty smokers and twenty non-smokers completed a brief Mood State Questionnaire every 2 hours, over one day shift and one night shift. The subjects comprised male police ocers and factory workers, aged 23±57 years. Cigarette smokers reported signi®cantly higher stress levels than non-smokers on both day and night shifts …p < 0:05†. This con®rms previous ®ndings that smokers are often more stressed than non-smokers. Stress levels varied over time within each shift …p < 0:001†, but the circadian patterns did not di€er between smokers and non-smokers. Thus smoking did not alter circadian mood rhythms, nor did it facilitate stress control. Self-rated levels of arousal showed the archetypal inverted-U pattern over time in both smokers and non-smokers. There was no di€erence in mean arousal levels between subgroups, indicating that cigarettes did not lead to greater alertness. The shift time interaction was signi®cant for both stress …p < 0:001† and arousal …p < 0:003†, indicating di€erent circadian rhythms during the day shift and the night shift. Finally, while smokers consumed slightly more cigarettes during the night shift than day shift (22.3, 19.4 respectively, p < 0:05), mean stress and arousal levels did not di€er between shifts. The implications of these ®ndings for smoking behaviour are discussed. # 1997 by John Wiley & Sons, Ltd. Stress Med., Vol. 13, 91±97 (1997) No. of Figures: 2. No. of Tables: 1. No. of Refs: 25.