BACKGROUND: Previous studies have reported the effects of direction of shift rotation on sleep, however, the findings are inconsistent. In this study, we investigated sleep quality related to direction of shift rotation using large-scale data from shiftwork-specific health examinations of electronics workers. METHODS: This study included 4750 electronics workers working in a rotating 3-shift system who completed a medical examination for shift workers survey from January 1 to December 31, 2014, at a general hospital. The subjects were categorized into one of two groups according to direction of shift rotation. We compared sleep quality index between the subjects who worked in forward rotation and backward rotation systems. RESULTS: Backward rotation was positively associated with prevalence of poor sleep quality. In the multivariable-adjusted model, when comparing backward rotation to forward rotation, the odds ratio (OR) with 95 % confidence interval (95 % CI) for poor sleep quality was 1.95 (1.58–2.41). After stratifying by gender, the ORs (95 % CIs) for poor sleep quality in male and female was 1.92 (1.47–2.49) and 2.13 (1.47–3.08), respectively. In subgroup analyses, backward rotation was significantly associated with poor sleep quality in workers ≥30 years of age compared with workers <30 years of age (adjusted OR 2.60 vs. 1.89, respectively; P for interaction <0.001). CONCLUSIONS: Our study supports that a backward rotation system is associated with poor sleep quality. Forward rotation systems should be considered to reduce sleep problems.
Female ; Hospitals, General ; Humans ; Male ; Odds Ratio ; Prevalence

BACKGROUND: We examined the association between insulin resistance assessed by homeostatic model assessment-insulin resistance (HOMA-IR) and benign prostatic hyperplasia (BPH) in healthy middle-aged male subjects. METHODS: A cross-sectional study included 1,727 male subjects, aged 40-59 year, free of medication history for BPH who received a transrectal ultrasonography and completed a structured questionnaire in 2011. Multiple logistic regression analysis was performed to evaluate the relationships of HOMA-IR with BPH across the tertile of HOMA-IR. RESULTS: The prevalence of BPH was 24.4% (421 out of 1,727). It was increased across HOMA-IR tertiles in crude and age-adjusted models. In a multivariable-adjusted model after adjusting potential confounders such as age, body mass index (BMI), triglyceride, high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), alcohol consumption, smoking, exercise and meat consumption, odds ratios (95% confidence intervals, CIs) of BPH for 2nd tertile and 3rd tertile compared to 1st tertile were 1.76 (1.31-2.35), and 1.83 (1.34-2.48), respectively. CONCLUSIONS: In middle-aged, healthy men, higher HOMA-IR was significantly associated with higher prevalence of BPH, supporting insulin resistance as an independent risk factor for BPH.
Alcohol Drinking ; Body Mass Index ; Cholesterol, HDL ; Cholesterol, LDL ; Cross-Sectional Studies ; Humans ; Insulin Resistance* ; Insulin* ; Logistic Models ; Male ; Meat ; Odds Ratio ; Prevalence ; Prostatic Hyperplasia* ; Risk Factors ; Smoke ; Smoking ; Triglycerides ; Ultrasonography