biostudies-literatureUnknown57(9)Horvath K<h4>Background</h4>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.<h4>Methods</h4>This 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 multilevel growth curve analysis of vocabulary development.<h4>Results</h4>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).<h4>Conclusions</h4>These results point to a longitudinal relationship between sleep and language development, with a particular emphasis on the importance of napping at this age.Journal of child psychology and psychiatry, and allied disciplines1008-17https://www.ebi.ac.uk/biostudies/studies/S-EPMC5017299biostudies-literatureFrequent daytime naps predict vocabulary growth in early childhood.PMC5017299Horvath KPlunkett KfalseFrequent daytime naps predict vocabulary growth in early childhood.<h4>Background</h4>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.<h4>Methods</h4>This 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 multilevel growth curve analysis of vocabulary development.<h4>Results</h4>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).<h4>Conclusions</h4>These results point to a longitudinal relationship between sleep and language development, with a particular emphasis on the importance of napping at this age.2016-01-01T00:00:00Z2016 Sep2021-02-20T23:25:02Z2019-03-27T02:23:52ZS-EPMC50172992732210210.1111/jcpp.12583