Associations between preschool sleep consolidation trajectories and receptive vocabulary at age 5.

Sleep is a key developmental context for receptive vocabulary acquisition during early childhood, yet little is known about how sleep consolidation trajectories are associated with subsequent receptive vocabulary development. This study aimed to identify sleep consolidation trajectories by examining child, maternal, and contextual factors in preschool ages, and testing their associations with receptive vocabulary at age 5. Three sleep consolidation trajectories emerged (n = 1912) from the Quebec Longitudinal Study of Child Development (QLSCD, 1997/1998): rapid (9.0%), typical (44.4%), and gradual (46.5%), based on daytime and nighttime sleep at 2.5, 3.5, 4 and 5 years of age. The multiple linear regression analysis showed that children in the gradual sleep consolidation trajectory had lower receptive vocabulary scores at age 5 (β = -0.10, 95% CI [-0.16, -0.03]) compared with those in the typical sleep consolidation trajectory. Having an immigrant mother (β = -0.31, 95% CI [-0.40, -0.22]) and receiving care outside certified childcare for children who never or occasionally attended childcare (β = -0.12, 95% CI [-0.19, -0.04]) and for those in relative-based care (β = -0.08, 95% CI [-0.16, -0.002]) were also associated with lower receptive vocabulary scores. Future research should replicate these results in recent cohorts and incorporate neurodevelopmental, and family contextual measures to clarify mechanisms through which the pace of sleep consolidation may influence receptive vocabulary acquisition.