Systematic review of the relationships between sleep duration and health indicators in the early years (0–4 years)

Abstract

BackgroundThe objective of this systematic review was to examine for the first time the associations between sleep duration and a broad range of health indicators in children aged 0 to 4 years.MethodsElectronic databases were searched with no limits on date or study design. Included studies (published in English or French) were peer-reviewed and met the a priori determined population (apparently healthy children aged 1 month to 4.99 years), intervention/exposure/comparator (various sleep durations), and outcome criteria (adiposity, emotional regulation, cognitive development, motor development, growth, cardiometabolic health, sedentary behaviour, physical activity, quality of life/well-being, and risks/injuries). The quality of evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework. Due to high levels of heterogeneity across studies, narrative syntheses were employed.ResultsA total of 69 articles/studies (62 unique samples) met inclusion criteria. Data across studies included 148,524 unique participants from 23 countries. The study designs were randomized trials (n = 3), non-randomized interventions (n = 1), longitudinal studies (n = 16), cross-sectional studies (n = 42), or longitudinal studies that also reported cross-sectional analyses (n = 7). Sleep duration was assessed by parental report in 70% of studies (n = 48) and was measured objectively (or both objectively and subjectively) in 30% of studies (n = 21). Overall, shorter sleep duration was associated with higher adiposity (20/31 studies), poorer emotional regulation (13/25 studies), impaired growth (2/2 studies), more screen time (5/5 studies), and higher risk of injuries (2/3 studies). The evidence related to cognitive development, motor development, physical activity, and quality of life/well-being was less clear, with no indicator showing consistent associations. No studies examined the association between sleep duration and cardiometabolic biomarkers in children aged 0 to 4 years. The quality of evidence ranged from “very low” to “high” across study designs and health indicators.ConclusionsDespite important limitations in the available evidence, longer sleep duration was generally associated with better body composition, emotional regulation, and growth in children aged 0 to 4 years. Shorter sleep duration was also associated with longer screen time use and more injuries. Better-quality studies with stronger research designs that can provide information on dose-response relationships are needed to inform contemporary sleep duration recommendations.Electronic supplementary materialThe online version of this article (10.1186/s12889-017-4850-2) contains supplementary material, which is available to authorized users.

The cross‐sectional and prospective associations between sleep characteristics and adiposity in toddlers: Results from the GET UP! Study

“…Moreover, it has been suggested that the adverse effect of short sleep duration on adiposity may be moderate during early childhood, which is likely to manifest over time if the short sleep duration is prolonged. In that case, it may not be easily observed in a younger and healthier population like our sample . Since preschoolers who have short sleep duration may also sleep less in their toddlerhood and infancy, there may be stronger accumulative effects on adiposity, and it may be easier to find significant associations, compared with toddlers.…”

“…A lack of adequate amount of sleep in school‐aged children and adolescents has been described to be one contributing factor to obesity . A recent systematic review in children under 5 years of age suggested that shorter sleep duration was associated with concurrent and later excess of adiposity in 20 (out of 31) studies . However, most of those studies focused on preschoolers (3‐5 years), whereas evidence in infancy and toddlerhood (prior to 3 years) is scarce and less consistent.…”

“…However, most of those studies focused on preschoolers (3‐5 years), whereas evidence in infancy and toddlerhood (prior to 3 years) is scarce and less consistent. In this review, only six studies had examined the association between sleep duration and adiposity in children under 3 years, with predominantly null findings (in four studies) . Since total sleep duration decreases across the first 3 years of life, understanding the nature of the association of sleep in this period would be important for preventing overweight and obesity.…”

“…3 A recent systematic review in children under 5 years of age suggested that shorter sleep duration was associated with concurrent and later excess of adiposity in 20 (out of 31) studies. 4 However, most of those studies focused on preschoolers (3-5 years), whereas evidence in infancy and toddlerhood (prior to 3 years) is scarce and less consistent. In this review, only six studies had examined the association between sleep duration and adiposity in children under 3 years, with predominantly null findings (in four studies).…”

Overnight sleep duration and obesity in 2–5 year‐old American Indian children

“…While multiple prior studies have demonstrated an increased risk of obesity with short sleep duration, this has not, to the best of our knowledge, been previously explored in AI children. While most prior studies examining this relationship have been performed in school‐aged children, a recent meta‐analysis including only children 0–4 years did find that 10 of 18 cross‐sectional and 10 of 13 longitudinal studies reported a significant association between shorter sleep duration and measures of adiposity . Importantly, sleep duration, obesity risk and their interaction may differ depending on culture.…”