Infant Sleep Disparities: Examining the Emergence of Differences in Infant Sleep Outcomes by Race/Ethnicity and Socioeconomic Status, and Implications for Childhood Obesity

Abstract

Almost a third of children in the United States are overweight or obese, with the highest prevalence among racial/ethnic minority children. [Ogden et al., 2014] The short- and long-term consequences of childhood obesity have long been established, as well as various behavioral risk factors, typically around children’s diet and physical activity. [Halfon et al., 2013; Olds et al., 2011; Reilly et al., 2003] More recently, research has also demonstrated a link between insufficient sleep and childhood obesity. [Cappuccio et al., 2008; Chen et al., 2008; Hart et al., 2011; Fatima et al., 2015; Ruan et al., 2015]. A 2008 systematic review and meta-analysis by Chen et al. revealed a significant inverse association between child sleep duration and obesity (OR: 1.58 [95% Confidence Interval [CI]: 1.26, 1.98]). Two meta-analyses consisting of only longitudinal studies have since been published, both finding that short sleep duration was associated with a significant increase in risk for overweight or obesity in children. [Fatima et al., 2015; Ruan et al., 2015] Evidence on the association between sleep duration and adiposity in infants, specifically, remains mixed. [Hiscock et al., 2011; Klingenberg et al., 2013; Taveras et al., 2008; Tikotzky et al., 2010] However, a longitudinal multivariate analysis conducted by Taveras et al. (2008) found that infants who slept less than 12 hours per day had higher BMI z-scores (β: 0.16 [95% CI: 0.02, 0.29]), as well as increased odds of obesity (OR: 2.04 [95% CI: 1.07, 3.91]). Further, evidence suggests that sleep patterns and behaviors in infancy are predictive of sleep outcomes in subsequent years, and research has consistently demonstrated other physical and mental health benefits of sufficient sleep in children. [Lam et al., 2003; Nevarez et al., 2010; Zuckerman et al., 1987] Like risk for obesity itself, disparities in childhood sleep outcomes have been observed, with children from racial/ethnic minority backgrounds and low-income households obtaining less sleep than their white and high-income counterparts. [Adam et al., 2007; Buckhalt et al., 2007; Crabtree et al., 2005; Dollman et al., 2007; Mindell et al., 2010; Nevarez et al., 2010; Spilsbury et al., 2004]. The objectives of this dissertation were to investigate the emergence of differences in sleep outcomes by race/ethnicity and socioeconomic status and to use both quantitative and qualitative data to examine contextual factors that may be contributing to these differences. Multivariable regression analyses revealed that Hispanic infants slept significantly less than non-Hispanic white infants at both 1- and 6-months of age. The association between race/ethnicity and nighttime sleep duration at 6-months could not be explained by socioeconomic status but was instead mediated by later bedtimes and less stringent sleep routines among Hispanic infants. Interview data supported and expanded upon these findings.