To investigate associations between shiftwork and diurnal salivary cortisol among 319 police officers (77.7% men).
Information on shiftwork was obtained from the City of Buffalo, NY electronic payroll records. Saliva was collected using Salivettes at seven time points and analyzed for free cortisol concentrations (nmol/L) using a chemiluminescence immunoassay. Mean slopes and areas under the curve were compared across shift schedule using analysis of variance (ANOVA)/analysis of covariance (ANCOVA).
Officers working primarily on the night shift had a significantly shallower slope. Mean slope (nmol/L/minutes) of the cortisol curve varied significantly across shifts (day: −0.00332 ± 0.00017, afternoon: −0.00313 ± 0.00018, night: −0.00257 ± 0.0002); adjusted P = 0.023.
Our results suggest that night shiftwork is a workplace factor that may alter the response of the hypothalamic–pituitary–adrenal (HPA) axis to the circadian cues responsible for the pattern of the diurnal cortisol curve.
Biostatistics and Epidemiology Branch (Drs Charles, Fekedulegn, Burchfiel, Hartley, and Andrew); Department of Epidemiology and Environmental Health, School of Public Health and Health Professions, State University of New York at Buffalo (Dr Violanti); Toxicology and Molecular Biology Branch (Dr Miller), Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia.
Address correspondence to: Luenda E. Charles, PhD, MPH, U.S. Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, HELD/BEB, MS L-4050, 1095 Willowdale Rd., Morgantown, WV 26505-2888 (firstname.lastname@example.org).
The first two authors contributed equally to this manuscript.
The authors report no conflicts of interest. The authors alone are responsible for the content and writting of the paper.
This work was supported by the National Institute for Occupational Safety and Health (NIOSH), contract no. 200-2003-01580. The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health.