Both frequency and duration of rotating night shifts are associated with metabolic parameters: a cross-sectional study

Background: Rotating night shift work contributes to the development of metabolic syndrome and relevant diseases. However, the contribution of different aspects of rotating night shift is rarely studied. Aim: This study investigated the association of frequency and duration of rotating night shift with metabolic parameters. Methods: A cross-sectional study was conducted in nurses. Socio-demographic characteristics, duration and frequency of rotating night shifts, and metabolic parameters including body mass index (BMI), fasting blood glucose (FBG), blood pressure (BP), triglyceride, total cholesterol (TC), low density lipoprotein cholesterol (LDL-C) and high density lipoprotein cholesterol (HDL-C), were collected. Sleep quality and perceived stress were assessed with Pittsburgh Sleep Quality Index (PSQI) and Perceived Stress Scale (PSS) respectively. Ratio of rotating night shift years to age (RRSYA) was calculated to present cumulative effect. Metabolic parameters were log-transformed and z-transformed in sequence. Multiple linear regressions were applied to explore the effect of frequency and RRSYA on metabolic parameters. Mediation analysis was used to estimate potential mediating effect of sleep quality and perceived stress. Results: Frequency of rotating night shift work was significantly associated with elevated FBG and BMI, and decreased LDL-C. RRSYA was significantly associated with higher BMI, TC, LDL-C, BP and FBG. Sleep quality exhibited significant mediating effect between rotating night shift features and FBG and BMI. Conclusions: Our results suggest that frequency and RRSYA are associated with metabolic profile alterations, but the effects are different. Sleep quality appears to be an important mediator of the night shift's metabolic effect. Proper shift arrangement and sleep quality assurance may reduce the negative metabolic changes.