Rotating night shift work, exposure to light at night, and glomerular filtration rate: baseline results from a Chinese occupational cohort

Abstract Background The misalignment between the circadian clock and behavioral cycles has been implicated in pathogenesis of many diseases. However, whether the kidneys are also more prone to disease in the circumstances of chronic circadian rhythms disruption due to night shift work and light at night (LAN) is unclear. The main purpose of this study is to examine the association between rotating night shift work, exposure to light at night, and glomerular filtration rate among steelworkers in north China. Methods A total of 6869 participants, aged 22 to 60 years, were included in this study. Multivariable logistic regression was used to examine the association between night shift work, the brightness of bedroom ambient light at night (LAN), and estimated glomerular filtration rate (eGFR) with adjustment for potential confounders. The relationship between duration of night shift work (continuous), cumulative number of night shifts (continuous), and eGFR were also examined using restricted cubic spline models. Results Long duration of night shift work (≥29 years) had elevated odds of decreased eGFR (OR, 1.39, 95% CI 1.10–1.75) compared with day work after adjustment for potential confounders. Negative associations between duration of night shift work, cumulative number of night shifts, and eGFR (mL/min/1.73 m 2 ) were observed in RCS models. No significant associations were observed among the different brightness of bedroom ambient light levels: middle level (OR, 0.90, 95% CI 0.77–1.05), lightest level (OR, 0.94, 95% CI 0.75–1.17), and decreased eGFR compared with the darkest level. Conclusion The increased duration of night shift work and cumulative number of night shifts among night shift workers, but not the brightness of bedroom ambient LAN, are associated with a slight decline of renal function among steelworkers.