STRESS AND AROUSAL CIRCADIAN-RHYTHMS IN SMOKERS AND NONSMOKERS WORKING DAY AND NIGHT SHIFTS

Twenty smokers and twenty non-smokers completed a brief Mood State Que stionnaire every 2 hours, over one day shift and one night shift. The subjects comprised male police officers and factory workers, aged 23-5 7 years, Cigarette smokers reported significantly higher stress levels than non-smokers on both day and night shifts (p < 0.05). This confir ms previous findings that smokers are often more stressed than non-smo kers. Stress levels varied over time within each shift (p < 0.001), bu t the circadian patterns did not differ between smokers and non-smoker s. Thus smoking did not alter circadian mood rhythms, nor did it facil itate stress control. Self-rated levels of arousal showed the archetyp al inverted-U pattern over time in both smokers and non-smokers. There was no difference in mean arousal levels between subgroups, indicatin g that cigarettes did not lead to greater alertness. The shift x time interaction was significant for both stress (p < 0.001) and arousal (p < 0.003), indicating different circadian rhythms during the day shift and the night shift. Finally, while smokers consumed slightly more ci garettes during the night shift than day shift (22.3, 19.4 respectivel y, p < 0.05), mean stress and arousal levels did not differ between sh ifts. The implications of these findings for smoking behaviour are dis cussed. (C) 1997 by John Wiley & Sons, Ltd.