Short persistent sleep duration is associated with poor receptive vocabulary performance in middle childhood

The aim of this study was to examine whether short sleep duration is associated with poor receptive vocabulary at age 10 years. In the Quebec Longitudinal Study of Child Development, parents reported their children's nocturnal sleep duration annually from ages 2.5 to 10 years, and children were assessed for receptive vocabulary using the Peabody Picture Vocabulary Test-Revised (PPVT-R) at ages 4 and 10 years. Groups with distinct nocturnal sleep duration trajectories were identified and the relationships between sleep trajectories and poor PPVT-R performance were characterized. In all, 1192 children with available sleep duration and PPVT-R data participated in this epidemiological study. We identified four longitudinal nocturnal sleep trajectories: short persistent sleepers (n = 72, 6.0%), short increasing sleepers (n = 47, 3.9%), 10-h sleepers (n = 628, 52.7%) and 11-h sleepers (n = 445, 37.3%). In all, 14.8% of the children showed poor PPVT-R performance at age 10 years. Nocturnal sleep trajectories and poor PPVT-R performance at age 10 were associated significantly (P = 0.003). After adjusting for baseline receptive vocabulary performance at age 4 and other potential confounding variables, logistic regression analyses suggest that, compared to 11-h sleepers, the odds ratio of presenting poor receptive vocabulary at age 10 was 2.67 [95% confidence interval (CI): 1.24-5.74, P = 0.012] for short persistent sleepers and 1.66 (95% CI: 1.06-2.59, P = 0.026) for 10-h sleepers. These results corroborate previous findings in early childhood, and indicate that short sleep duration is associated with poor receptive vocabulary during middle childhood.