Rotating Night Shift Work, Exposure to Light at Night, and Glomerular Filtration Rate: Baseline Results from a Chinese Occupational Cohort

Abstract

The misalignment between the circadian clock and behavioral cycles has been implicated in pathogenesis of many diseases. 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. A total of 6869 steelworkers, 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. Mediation analysis was performed to examine the mediation effect of potential mediators on the association of duration of night shifts and eGFR. Long duration of night shift work (≥29 years) had elevated odds of decreased eGFR (≤89 mL/min/1.73 m2) (odds ratio (OR), 1.37, 95% confidence interval (CI) 1.09–1.73) compared with day work after adjustment for potential confounders. The association between duration of night shifts and eGFR (continuous) was partially modified by diastolic blood pressure (average causal mediation effect (ACME), –0.077, 95% CI –0.134 to −0.030, p < 0.001). 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 0.75–1.18), and decreased eGFR compared with the darkest level. Long-term night-shift work, rather than the brightness of bedroom ambient LAN, is associated with early stage of renal dysfunction in steelworkers, and blood pressure may mediate the relationship between night shift work and decreased eGFR.

A longitudinal study of working hours and chronic kidney disease in healthy workers: The Kangbuk Samsung Health Study

“…Only a few previous studies have demonstrated the association between CKD and work‐related factors such as working hour, shift work, and job stress. 11 , 12 , 21 A cohort study of Chinese steelworkers reported that long‐term night shift work was associated with a higher risk of early stages of renal disease mediated by BP. 12 Furthermore, shift workers who worked in irregular, split, and rotating shifts tended to work for longer duration due to less work schedule flexibility.…”

“…To explore whether clinical factors mediated the association between working hours and CKD, 11 , 19 , 20 Model 3 was further adjusted for BMI, systolic blood pressure, fasting blood glucose, HOMA‐IR, uric acid, and hsCRP. To clearly elucidate the effect of working hours on CKD, 12 , 21 Model 4 was further adjusted for work‐related factors, such as work shift schedule and total KOSS‐SF score. A proportional hazards assumption was tested by examining the graphs of estimated log (−log) survival and using “ estat phtest ” command based on Schoenfeld residuals.…”

“…However, only a few studies have reported the relationship between working characteristics and CKD. 11 , 12 A cross‐sectional study showed that long working hours are associated with decreased estimated glomerular filtration rate (eGFR). 11 Therefore, our longitudinal study aimed to further examine the direct relationship between long working hours and incident CKD.…”

Association of Rotating Night Shift Work with Body Fat Percentage and Fat Mass Index among Female Steelworkers in North China

“…This was a cross-sectional study conducted at 11 steel production departments owned by the HBIS Group’s Tangsteel Company in Tangshan City, Hebei Province in north China. The study design and population have been described in detail in our previous studies [ 18 , 19 , 20 ]. Given that a previous study has evaluated the association between night shift work and obesity among male steelworkers in this population, the present study only included female workers [ 21 ].…”

“…The main work schedule of the present study population has been introduced in detail in our previous research [ 19 , 20 ]. In brief, shift work in this study refers to rotating night shifts (the mainly four-crew-three-shift system now and historical three-crew-two-shift system).…”