Melatonin Patterns Among Female Hospital Employees On Day And Night Shifts: Assessment By Different Exposure Metrics
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Objective: To assess the associations of different shift work exposure metrics with circadian melatonin mesor, amplitude and acrophase. Methods: In a cross-sectional study of 328 female hospital personnel working fixed-day or rotation schedules, shift work exposure metrics were determined through self-report. 6-sulfatoxymelatonin concentrations were analyzed by cosinor analysis. Results: Shift workers working at night had lower mesors and earlier acrophases than day workers. Shift workers working three or more consecutive nights had lower mesors and smaller amplitudes than those working less than three consecutive nights. After adjusting for confounders, acrophases were no longer different, while smaller amplitudes were apparent among shift workers compared to day workers. Shift length or duration of shift work were not associated with melatonin pattern. Conclusion: Rotating patterns of shift work, specifically high intensity rotations, are associated with depressed melatonin rhythms, an indicator of circadian disruption.