Relationship Between Workplace Noise Exposure and Sleep in Tanzania.

BACKGROUND: High noise levels during daytime work may cause sleep disturbances amongst workers, but research findings are inconclusive so far. OBJECTIVE: This study aims to compare sleep amongst workers exposed to high and low daytime noise during work in a developing country, where workplaces often have high noise levels. METHODS: A cross-sectional study was conducted amongst 181 metal industrial workers (high-noise-exposed workers) and 72 office cleaners (low-noise-exposed workers) in Tanzania. The average noise levels were 97.9 and 76.6 dBA for the high- and low-noise-exposed workers, respectively. An interview-based questionnaire was used to collect data on sociodemographic characteristics, sleep variables, the Epworth sleepiness scale (ESS) and the Bergen insomnia scale (BIS). Data were analysed using descriptive statistics, t-tests, Kruskal-Wallis tests, Pearson chi-square tests and logistic regression analysis. RESULTS: The mean BIS score for high-noise-exposed workers was 13.2, with 40.3% reporting insomnia and 39.8% reporting excessive daytime sleepiness (ESS ≥ 11). The low-noise-exposed workers had a mean BIS score of 15.4, with 51.4% reporting insomnia and 41.7% reporting excessive daytime sleepiness. The crude odds ratio (OR) of insomnia when exposed to high noise was 1.56 (95% CI = 0.90-2.718, P = 0.111), and the crude OR for excessive daytime sleepiness was 1.08 (95% CI = 0.62-1.88, P = 0.782). Insomnia and daytime sleepiness were not different between groups when adjusting for age, marital status, education, smoking, alcohol, coffee consumption and daytime rest periods. CONCLUSION: No differences were found between daytime high- and low-noise-exposed workers in relation to self-reported sleep variables. The results must be interpreted with caution due to the use of self-reports and possible unmeasured confounders.