Previous studies have shown negative effects of shift work on health, due to the desynchronization and resynchronization of biological rhythms. In these studies, among other parameters, indicators of cardiac dynamics were used, such as parameters of R-R interval variability, reduction in what has been considered a good predictor of health problems by some authors. The aim of this study was to determine the possible effects of shift work on the parameters of cardiac dynamics and the job perceptions of nurses of different lengths of service. The study included 48 nurses divided in two groups (24 nurses in each) of equal age and length of service. One group worked a three-shift rotation system and the other (control) worked only the day shift. On the basis of length of service, the groups were divided into three comparable subgroups with eight participants: 1–10, 11–20 and 21–30 years of service. Cardiac activity (R-R intervals) was monitored continuously during the morning shift using the Data Logging System. The participants also evaluated their satisfaction with the job, the difficulty of the work, and the impact of working hours on other aspects of life. Analysis of the results showed reduced variability in cardiac activity (DM-index) in the shift workers with up to 20 years of service, as compared with the comparative groups of day workers, which indicates a less favourable health dynamic. Differences among the oldest groups were not found, which can be attributed to spontaneous selection, where shift workers with health problems are transferred to the day shift. The shift workers were less satisfied with their job, assessing it as more difficult than the daytime workers, and showed a greater level of negative impact of working hours on other domains of life. Despite the specific and limited sample, resulting from difficulties in collecting the psychophysiological variables, the results show a satisfactory reliability and point to an adverse job perception and a cardiac dynamic less favourable for health.

cardiac dynamics, health, job satisfaction, nurses, R-R intervals, shift work