Does shift work lead to poorer health habits? A comparison between women who had always done shift work with those who had never done shift work

Shift work has been reported to predict health problems, and a possible explanation is that shift work may lead to poorer health habits, thereby increasing a person's vulnerability to illness. This study examined the association between shift work and health habits, as indicated by smoking, alcohol intake, physical activity and by being overweight. A questionnaire was sent to all 2795 female nurses working in the 10 hospitals of two Finnish health care districts. From the 2299 respondents, we selected those 506 shift workers who reported having always done shift work and those 183 day workers who had never done shift work. Shift workers were found to smoke more and to be overweight more often than day workers. These differences gradually increased in each successive age group, being 1.94 pack-years in smoking and 0.9 kg m^-2 in body mass index among nurses over 45 years of age. Shift work was not associated with alcohol intake or sedentary lifestyle. This evidence is compatible with the possibility that shift work in nurses increases smoking and being overweight to a degree that contributes to health problems, including coronary heart disease.