Rotating shift work time is directly associated with excess body adiposity

OBJECTIVE

To analyze the association between changes in body adiposity and length of service on a schedule of rotating shifts.

METHODS

The study was a cross-sectional investigation conducted during the years 2012, 2015, and 2018, involving individuals engaged in rotating shifts at a company involved in iron ore extraction situated within the Iron Quadrangle region of Minas Gerais and the southeastern region of Pará, Brazil. Sociodemographic and behavioral data were collected along with anthropometric parameters in order to calculate body mass index (BMI) and the waist-to-height ratio (WHtR). For data analysis, a multivariate logistic regression was employed to explore potential associations between indicators of body adiposity and the duration of shift work, employing a hierarchical determination model.

RESULTS

The findings showed that in the multivariate model, controlling for confounding factors, workers with 5 to 10, 10 to 15, and more than 15 years of shift work had 41 to 96% greater odds of being overweight (BMI > 25.0 kg/m2), 71 to 82% of having altered neck circumference (> 40 cm), 33 to 120% of altered WC (>102 cm), and 57 to 214% of having altered WHtR (> 0.5 cm).

CONCLUSION

The findings suggest that time spent in work has a significant effect on anthropometric indicators of body adiposity, especially if the worker has a previously established comorbidity such as dyslipidemia or hypertension and is frequently exposed to night work.

Vitamin D deficiency and hyperglycemia in male rotating shift workers: A disturbed circadian rhythms influence

BACKGROUND

Shift work is related to several negative impacts on the health of workers. This study aimed to evaluate the association between vitamin D deficiency (VDD) and hyperglycemia in shift workers.

METHODOLOGY

This cross-sectional study included male rotating shift workers in an iron ore extraction company. Participants were classified as VDD when 25(OH)D < 20 ng/mL for a healthy population and 25(OH)D < 30 ng/mL for groups at risk for VDD. Hyperglycemia was classified when fasting glucose ≥100 mg/dL or HbA1c ≥ 5.7%. Data were compared using chi-square analysis with Cramer's V as effect size, and Bonferroni correction. Multivariate logistic regression, from a model of determination, was performed to investigate whether VDD was associated with hyperglycemia.

RESULTS

The study evaluated 1411 workers, most workers were aged 30-39 years (53.2%), and 77.5% self-declared as black, brown, with up to complete high school (71.4%) and working alternate shifts for more than 5 years (76.1%). Regarding glucose and vitamin D, 32.0% and 29.1% of the workers had hyperglycemia and VDD, respectively. In multivariate analysis, controlled for confounding factors, workers with VDD had a 119% increased chance of hyperglycemia (OR: 2.19; IC95%: 1.56-3.08). Furthermore, vitamin D levels in distribution quintiles showed a dose-response gradient in relation to hyperglycemia, where increased vitamin D values were associated with a reduction in the occurrence of hyperglycemia.

CONCLUSION

Rotating shift workers with vitamin D deficiency are more likely to have hyperglycemia.