Influence of socioeconomic status on objective sleep measurement: A systematic review and meta-analysis of actigraphy studies

Social inequities have many health effects; one of these is a potential relationship to sleep disturbances. Socioeconomic status (SES) is an important factor that contributes to social inequities. SES is a marker of living conditions and habits that influence health by way of different processes, including stress-related mechanisms. However, a systematic review of the relationship between SES and objectively measured sleep parameters has not been conducted. Therefore, a systematic review and meta-analysis were performed to examine the relationship between SES and sleep parameters measured with actigraphy in the general population. Nineteen articles were identified and included from a keyword search in Medline/PubMed, Web of Science, and SCOPUS, following PRISMA guidelines. For an article to be included, it had to have a measure of SES and also, an actigraphy-based measure of sleep. For, included studies, qualitative and quantitative data were extracted, and study quality was assessed with The National Institute of Health's Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. Bivariate correlations were extracted and entered into a meta-analysis, along with a qualitative review of articles. These analyses revealed that SES was associated with sleep parameters in the predicted direction, with lower SES associated with worse sleep parameters. Specifically, lower SES was associated with lower total sleep time, longer sleep latency, greater sleep fragmentation, and higher variability in sleep onset and sleep latency. Higher education, higher perceived economic well-being, and higher income were significantly associated with improved sleep efficiency and longer sleep duration. For the 19 articles included, 10 were rated as fair or poor in study quality. Thus, higher quality studies in this area are needed. This meta-analysis and systematic review demonstrated that social inequities of sleep can be measured objectively, opening the path to the development and integration of methodologies combining actigraphy with current subjective measures for utilization in clinical practice.