Aim: This paper is a report of a study to investigate if an irregular rotating shift system, including night shifts, can cause changes to the secretion of hormones in nurses.
Method: In 2006, 32 healthy intensive care unit nurses completed the Standard Shiftwork Index (SSI) and blood samples were collected from each participant at the beginning and end of each shift. Change in hormone levels between the beginning and end of morning shifts were examined and compared between nurses on morning only and rotating shifts. Correlations between change in hormone concentrations and scores from the SSI are presented.
Results: The mean reduction of cortisol level between the two measurements was statistically significantly greater for the 'rotating' than 'morning' shift group (P = 0.032). There were no statistically significant differences between the two groups in overall mean change from the first to the second measurement of prolactin, triiodothyronine and thyroid-stimulating hormone. Levels of thyroxine increased statistically significantly in the 'rotating' group (P = 0.049) but not in the 'morning' group. The morningness scale score was greater for the 'rotating' group, while greater job satisfaction levels were found in the 'morning' group. Statistically significant correlations were found between thyroid-stimulating hormone, triiodothyronine, thyroxine and prolactin changes and specific scales of the SSI questionnaire.
Conclusion: Ergonomic shift schedules sympathetic to the body clock and nurses' preferences should be adopted to mitigate the adverse effects on health.