Association between sleep duration and academic, cognitive and socioeconomic outcomes: A systematic literature review of population-based studies

The aim of this study was to systematically review the literature about the relationship between sleep duration and cognitive, academic and socioeconomic outcomes. We performed a systematic search in PubMed, Psyinfo, Scopus, Web of Science, ERIC, and Socindex up to June 2022, independently by two researchers. Original studies testing the association between sleep duration (as exposure) and academic, cognitive and socioeconomic variables (as outcomes) among all age groups in population-based studies were included. We excluded studies assessing participants with specific diseases or specific populations. Quality assessment was evaluated considering three domains: internal validity, study design, and adjustments. After the study selection process, a total of 56 manuscripts were selected. Most studies were from high-income countries with a large variability of instruments and cutoff points to measure sleep duration and outcomes. Cognitive outcomes were evaluated in 35 manuscripts, academic outcomes in 22, and socioeconomic outcomes in one. Long sleep seems to be associated with poor cognitive outcomes in older adults. In contrast, short sleep duration seems to be associated with poor cognitive and school outcomes among children and adolescents. Studies evaluating cognition in children and adolescents and academic outcomes presented lower scores in the quality assessment. More well designed and well-adjusted studies evaluating cognitive and academic outcomes in children, adolescents, and mainly, in adult population are necessary. Furthermore, studies from low- and middle- income countries, evaluating sleep duration and exploring the relationship between sleep duration as exposure variable and human capital characteristics as outcomes variables should be included in the research agenda.