Shift work is known to have a number of negative effects on the life and health of employees. It can lead to the disorganization of social and family life as well as many psychophysiological problems that can affect health in the long term. Moreover, it is likely to favour the development of eating habits which do not meet the requirements of general health standards. It is well known, for instance, that a positive correlation exists between the number of years spent employed on shift work and the occurrence of obesity. This type of work schedule could influence eating habits, thus contributing to obesity by either modifying the diet (i.e.?introducing unhealthy food) or by producing abnormal food intake schedules. The main purpose of this study was, therefore, to focus on the relationship between eating habits and work schedules, as a function of possible sleep-wake cycle modifications due to shift work, as well as on possible specific motor activity. Twenty-eight nurses volunteered to participate in this experiment. Subjects were divided into four groups as a function of weight (obese/normal) and work schedules (shift work / normal). Motor activity was measured by means of an actimeter over a period of 14?days and nights. These objective measures were then correlated with subjective assessments on qualitative and quantitative information concerning eating habits and sleep quality. These measures were completed with qualitative ratings and affective reactions produced by obesity.
The actimetric results suggested evidence of a specific difference in the motor activity of obese workers compared to normal weighted workers, namely hypo-activity. Questionnaires also showed different eating habits and sleep quality in obese shift workers as compared to the other groups. Namely, the frequency of nibbling between main meals was significantly higher in this group than in obese nurses working on regular day schedules and in normal weighted shift workers. This group was also the one which assigned the cause of obesity to stressful activity and which attributed to it the origin of their negative affect. However, there was no evidence of a specific diet in obese subjects, ruling out, at least under our experimental conditions, the possibility that food characteristics by themselves could participate to the development of obesity. In conclusion, this study suggests that obesity in shift workers could be mainly due to abnormal schedules of food intake rather than to the nature of the diet alone.