Association between sleep duration and attention-deficit hyperactivity disorder: A systematic review and meta-analysis of observational studies

Background: Several previous meta-analyses have investigated the association between sleep quality and attention-deficit/hyperactivity disorder (ADHD). To examine the relationship between short or long sleep duration and ADHD, a meta-analysis of observational studies was conducted. Methods: The PubMed, EMBASE, and Cochrane Library databases were systematically searched in March 2019 to retrieve observational studies. A random-effects model was used to analyze meta-estimates of sleep duration. Three evaluators independently reviewed and selected the articles based on pre-determined selection criteria. Results: Of 1466 articles retrieved, 10 observational epidemiological studies, comprising six case-control studies and four prospective cohort studies, were included in the final analysis. Short sleep duration was significantly linked to ADHD compared with average sleep duration (odds ratio [OR] or relative risk [RR] 1.28 [95% confidence interval (CI) 1.16-1.41]), and especially with hyperactivity (OR/RR 1.60 [95% CI 1.18-2.17]). Subgroup meta-analyses according to various factors, such as study design, number of participants, methodological quality, and adjustment for smoking status and education, yielded consistent results. A significant association between long sleep duration and ADHD was not observed. Limitations: Publication bias and substantial heterogeneity due to the diverse measurement tools used to determine ADHD were observed. Lack of prospective cohort studies was another limitation. Conclusion: Short sleep duration was associated with ADHD in the current meta-analysis. Clinicians may need to be more aware of this association.