Social disparities in sleep health of African populations: A systematic review and meta-analysis of observational studies

OBJECTIVES: To document the relationship between socioeconomic status (SES) and sleep health in African populations. METHODS: Observational cross-sectional or cohort studies examining the association between SES indicators and sleep outcomes in participants from African countries were included. The search was performed in the MEDLINE, Embase, and Web of Science Core Collection electronic databases in June 2021. Selection, confounding, attrition/exclusion, detection, and selective reporting bias were assessed using the OHAT Risk of Bias Tool. Random effects meta-analysis was used for summarizing the effect estimates. RESULTS: Forty-three reports were selected, having sampled 153,372 Africans from 26 countries. Education was the most frequent SES indicator and composite measures of sleep quality or disturbances was the most common sleep outcome. Low educational attainment was significantly associated with lower odds of short sleep (odds ratio [OR]=0.65, 95% confidence intervals [0.50, 0.84], p = .001) and higher odds of insomnia (OR=1.53, [1.18, 1.99], p = .001) or poor sleep quality (OR=1.60, [1.17, 2.18], p = .003). Low levels of income/assets were related to higher odds of insomnia (OR=1.38, [1.02, 1.86], p = .04) and low occupational/employment status was linked to lower odds of short sleep duration (OR=0.49, [0.30, 0.79], p = .004). CONCLUSIONS: Socioeconomic disadvantage was a significant predictor of insomnia and poor sleep quality, while it was associated with longer sleep duration. Significant heterogeneity in terms of exposure and outcomes, scarcity of longitudinal designs, lack of objective outcome measurement, and low representation of rural samples and participants from low-income countries limit the quality of evidence.