Salivary melatonin and cortisol and occupational injuries among Italian hospital workers.

Stress, circadian patterns, and sleep-related factors may have a role on occupational injuries. We investigated the association between occupational injuries among the workers of an Italian hospital and their secretion of salivary melatonin and cortisol. We used a case-control study design. 27 injured cases and 31 non-injured controls provided 5 salivary samples every 60 min from 9 pm to 1 am. Melatonin and cortisol concentrations were measured, and the Dim Light Melatonin Onset (DLMO) derived using two fixed thresholds (1 and 3 pg/mL). The associations between injury, melatonin, cortisol, and DLMO were assessed through univariate and multivariate analyses. Non-injured controls had higher melatonin (median 2.28 pg/mL) and lower cortisol concentrations (0.71 ng/mL), as well as earlier DLMO times (9:00 pm with the 1 pg/mL melatonin cutoff) than cases (1.01 pg/mL, 1.14 ng/mL and 9:12 pm, respectively), although only few results were statistically significant. Measuring these hormones might be helpful to characterize the risk of injury among hospital workers.