标题：Analysis of salivary cortisol levels to determine the association between depression level and differences in circadian rhythms of shift-working nurses
摘要：Objective: The aim of this study was to clarify whether there are differences in the circadian rhythms of shift-working nurses by assessing depression, fatigue and salivary cortisol levels. Methods: Forty nurses working in a two-shift system at “Hospital A”, Fukuoka City, Japan, used a self-rated depression scale (SDS) to assess their depression levels. Fatigue levels were measured with the visual analogue scale for fatigue (VAS-F); saliva was collected before and during shifts for three days. Results were analyzed with analysis of variance (ANOVA). Results: Thirty-six valid records were obtained, and subjects were classified according to SDS scores into a normal group (NG), moderate group (MG) and severe group (SG). There were no significant differences in the day shift salivary cortisol values of the three groups. However, the night shift salivary cortisol value for the SG was 0.132 µ g/d l at 16:00, before starting the shift, and decreased to 0.036 µ g/d l at 20:00. It increased slightly up to 0.057 µ g/d l by 24:00 and formed a peak between 5:00 and 7:00, with the levels being 0.322 µ g/d l and 0.305 µ g/d l respectively. Meanwhile, the NG cortisol value was 0.154 µ g/d l before the shift, decreased to 0.034 µ g/d l by 20:00, slightly increased up to 0.093 µ g/d l by 5:00 and presented its peak value, 0.253 µ g/d l , at 7:00 next morning. Conclusions: SG nurses presented significantly increased salivary cortisol levels early in the morning during night shifts, showing a phase deviation in the circadian rhythm. Because subjective fatigue levels did not differ with time, SG nurses should understand and deal with physical changes in the early morning. This approach may reduce medical accidents and malpractice in the early morning.(J Occup Health 2015; 57: 237–244)
