Frequent daytime naps predict vocabulary growth in early childhood

Journal article

Background: The facilitating role of sleep for language learning is well-attested in adults and to a lesser extent in infants and toddlers. However, the longitudinal relationship between sleep patterns and early vocabulary development is not well understood.
Methods: The current study investigates how measures of sleep are related to the development of vocabulary size in infants and toddlers. Day and night-time sleeping patterns of infants and toddlers were compared with their concurrent and subsequent vocabulary development. Sleep assessments were conducted using a sleep diary specifically designed to facilitate accurate parental report. Sleep measures were used as predictors in a multi-level growth curve analysis of vocabulary development.
Results: The number of daytime naps was positively associated with both predicted expressive (p = .062) and receptive vocabulary growth (p = .006), whereas the length of night-time sleep was negatively associated with rate of predicted expressive vocabulary growth (p = .045). Sleep efficiency was also positively associated with both predicted receptive (p = .001) and expressive vocabulary growth (p = .068).
Conclusions: These results point to a longitudinal relationship between sleep and language development, with a particular emphasis on the importance of napping at this age.

Authors: Horvath, K; Plunkett, K

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Wiley
• Journal: Journal of Child Psychology and Psychiatry
• Publication date: 2016-06-20
• DOI: 10.1111/jcpp.12583
• EISSN: 1469-7610
• ISSN: 0021-9630
• Keywords: sleep; infants; children; nap; vocabulary development