Actigraphy-Measured Sleep and Growth Trajectories During the First Two Years of Life: Longitudinal Evidence from a Birth Cohort

Study Objectives This study aims to examine associations between changes in objectively measured sleep characteristics and growth trajectories, as well as risk of rapid weight gain (RWG) and overweight in infants. Methods The study analyzed data from 298 healthy term infants (48.7% boys) in the Sleep Health in Infancy & Early Childhood (Rise & SHINE) birth cohort, with sleep measured by actigraphy at 1 and 6 months. Changes in nighttime sleep duration, fragmentation (wake after sleep onset [WASO], waking bouts, sleep efficiency), and regularity (sleep regularity index [SRI]) were examined as exposures. Growth trajectory parameters—size, tempo, and velocity—were modeled from repeated anthropometric measurements using SuperImposition by Translation and Rotation (SITAR), and weight outcomes at 24 months included RWG and overweight. Associations between sleep changes and growth outcomes were examined using linear and logistic regression models. Results In adjusted models, a 1-hour increase in WASO between 1 and 6 months was associated with greater weight size (β = 0.093; 95% CI, 0.019 to 0.166), as well as higher odds of RWG (OR, 2.39; 95% CI, 1.02 to 6.07) and overweight (OR, 2.66; 95% CI, 1.16 to 6.16). A 5% decrease in sleep efficiency was associated with greater weight size (β = 0.059; 95% CI, 0.020 to 0.099) and slower weight velocity (β = -10.013; 95% CI, -18.693 to -1.332). A 5% decrease in the sleep regularity index was associated with later length tempo (β = 0.004; 95% CI, 0.001 to 0.007). No associations were observed for sleep changes with WFL trajectories. Conclusions Early sleep patterns may serve as a modifiable factor in preventing future obesity.