Associations between sleep, dietary intake and physical activity in children: systematic review

Background: Inadequate sleep duration is a significant risk factor for obesity in children. However, the mechanism by which poor sleep increases the risk for obesity in childhood is unclear. It is hypothesized that sleep may be linked to obesity via alterations in key lifestyle practices. Objectives: This systematic review aims to investigate whether an association exists, in either direction, between poor sleep quantity/ quality and: a) poor dietary intake/behaviors; b) sub-optimal physical activity and sedentary behavior patterns, in children and adolescents aged 3-18 years. Inclusion criteria: Studies were eligible for inclusion if participants were healthy and aged 3-18 years. Studies were excluded if the population had known co-morbidities. Exposure variables were sleep quantity/ quality and physical activity/ dietary intake. Both directions of the association were considered. Study types: The review considered any epidemiological study design, if they assessed the association between sleep quantity/ quality and dietary patterns or physical activity/ sedentary behavior. Outcomes: Outcome measures were dietary intake and physical activity/ sedentary behavior (after exposure to poor sleep quantity/quality) and sleep quantity/ quality (after exposure to poor dietary behavior or sub-optimal physical activity/ sedentary behavior). Search strategy: The search strategy aimed to find both published and unpublished studies in the English language from January 1970 to March 2011. Electronic databases included PubMed, CINAHL, Scopus, online Australian Digital Theses Program and Dissertation Abstracts, and Mednar. Methodological quality: Critical appraisal was undertaken by two independent reviewers using the standardized critical appraisal instrument from the Joanna Briggs Institute Meta-Analysis of Statistics Assessment and Review Instruments. Data collection/ synthesis: Using the appropriate Joanna Briggs Institute Meta-Analysis of Statistics Assessment and Review Instrument, information was extracted including population demographics; method of sleep, dietary intake, physical activity and sedentary activity collection; sleep quantity/ quality, dietary intake, physical activity/ sedentary behavior findings. Data from included studies were presented in tables and as a narrative summary. Results: Of a total of 414 studies identified, seven cross-sectional studies met the inclusion criteria and underwent critical appraisal and data extraction. Included studies had a collective sample size of n=8849, evenly distributed male: female ratio, and age range 7-15 years. Five studies reported activity and sleep-related outcomes and five reported dietary and sleep-related outcomes. The majority of studies used subjective assessment of outcomes. Several studies reported reduced sleep duration and insomnia symptoms and associations with dietary patterns, physical activity, and sedentary behavior. Conclusions: To investigate how poor sleep quantity/ quality may increase obesity risk in children and adolescents, well-designed longitudinal and intervention studies to explore the direction of the association between childhood sleep and dietary/ activity practices are needed