0264 Objective Sleep Health and Rapid Weight Gain Across the First Two Years of Life: Longitudinal Autovideosomnography Findings from a Two-Cohort Study

Abstract Introduction Rapid weight gain (RWG) in infancy is a strong predictor of later obesity, yet the contribution of objectively measured sleep health remains poorly understood. Most previous RWG–sleep studies rely on caregiver-reported sleep; only limited recent work incorporates actigraphy, and none use autovideosomnography to characterize multidimensional sleep health across the first two years of life. This study examined associations between sleep duration and other dimensions of objectively measured sleep health with RWG from birth to 24 months. Methods Infants were enrolled shortly after birth and completed sleep assessments at 6, 12, 18, and 24 months. In-home autovideosomnography estimated total sleep time (TST), sleep onset timing, wake after sleep onset (WASO), and nighttime awakenings. RWG was defined as >0.67 SD increase in weight-for-length/BMI z-score between visits. Analyses reflect the complete Cohort 1 dataset; Cohort 2 will broaden sample representation, with full dataset availability expected in January/February 2026. Results At the 6-month assessment, valid sleep data were available for 252 infants (44.3% female). Caregiver respondents were predominantly non-Hispanic White (67.5%), biological parents (86.0%), married (83.4%), and college educated (73.1%). RWG prevalence was 18.6%, 27.1%, 19.0%, and 6.9% for birth–6, 6–12, 12–18, and 18–24 months, respectively. No RWG–sleep associations were observed from birth to 6 months. At 12 months, infants with RWG (n=16) slept 37.35 minutes less per night than those without RWG (n=36) (t=2.94; p=.008). At 18 months, infants with RWG (n=2) slept 35.01 minutes longer per night than infants without RWG (n=22) (t=–3.30; p=.02). Sleep onset timing, WASO, and nighttime awakenings showed no significant associations with RWG at any age. Conclusion Cohort 1 findings suggest that shorter nocturnal sleep duration in late infancy may be associated with RWG, while other sleep dimensions did not differ by RWG status. The contrasting directionality observed at 18 months, based on a small RWG subgroup, may reflect developmental variability and warrants further investigation. The full two-cohort dataset available in early 2026 will support deeper evaluation of early sleep–growth relationships and inform obesity prevention targets. Support (if any) PRIME pilot funding, Yale School of Nursing