Night Shift Work and Poor Sleep Quality Among Female Workers in Southern Brazil: A Repeated Cross-Sectional Study (2017-2022).

Purpose: Night shift work has been identified as a significant risk factor for various health issues, particularly among women, whose vulnerability to poor sleep quality may be exacerbated by sociocultural and occupational dynamics. In this study, we examined the association between night shift work and poor sleep quality among female workers. Patients and Methods: This repeated cross-sectional study is part of a broader investigation entitled "Health Conditions of Female Shift Workers: A Longitudinal Occupational Health Study" (ELO SAÚDE). The study was conducted among adult female factory workers employed by the same industrial group in southern Brazil, with data collected in 2017 (n = 394) and 2022 (n = 399). Poor sleep quality was defined as a Pittsburgh Sleep Quality Index (PSQI) score > 5. Night shift work was characterized by work schedules starting and ending between 10:00 PM and 6:00 AM. Prevalence ratios (PR) and 95% confidence intervals (CI) were estimated using Poisson regression with robust variance. Results: The mean age of participants was 35.8 ± 9.1 years in 2017 and 34.2 ± 9.9 years in 2022. The prevalence of poor sleep quality increased significantly from 58.3% (95% CI: 53.4-63.2%) in 2017 to 67.7% (95% CI: 63.0-72.3%) in 2022 (p = 0.007). After adjusting for potential confounders, night shift work was associated with a 30% higher prevalence of poor sleep quality in 2017 (PR = 1.30; 95% CI: 1.10-1.55; p = 0.002) and 25% higher in 2022 (PR = 1.25; 95% CI: 1.10-1.43; p < 0.001). Conclusion: Poor sleep quality remains highly prevalent and significantly associated with night shift work among female workers, with a notable increase over time. Thus, interventions focused on enhancing sleep hygiene and optimizing shift schedules are warranted in this population.