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Sleep in Relation to Preschoolers’ Narrative Comprehension: The Interaction Effect and Mediating Role of Verbal Working Memory
Poster Session C, Thursday, October 1, 10:45 am - 12:45 pm, Wangari Maathai
Lu Li1, Jueyao Lin1, Jiayi Lu1, Changsheng Li1, Zhengqin Liu1, Cehao Yu1, Han Zhang2, Caicai Zhang1; 1The Hong Kong Polytechnic University, 2ShanghaiTech University
Introduction: Sleep is increasingly recognized as a key biological foundation supporting early cognitive and language development. The preschool years represent a pivotal period of rapid brain maturation; however, evidence linking early sleep/wake patterns to higher-order language abilities, such as narrative comprehension, remains limited. While adequate nighttime sleep duration is essential for neurodevelopment (Astill et al., 2012), high intraindividual variability (IIV), or sleep irregularity—a critical dimension of sleep/wake patterns—has been identified as a predictor of cognitive decrements independent of average sleep duration (Becker et al., 2017). Nevertheless, the relative contributions of sleep duration and sleep regularity to narrative comprehension are understudied. Another limitation concerns the potential mediating role of working memory in the sleep-language relationship, given the established associations between sleep and working memory, and between working memory and narrative skills in preschoolers (Nieto et al., 2022; Scionti et al., 2023). This study addresses these gaps by examining the main and interaction effects of sleep duration and sleep regularity on preschoolers’ narrative comprehension, and exploring verbal working memory as a mechanistic bridge underlying these associations. Methods: Sixty-seven typically developing Cantonese-speaking children (4.52 ± 0.27 years; 28 males) in Hong Kong wore a GENEActiv actigraph for seven consecutive days, while parents completed sleep diaries. Sleep measures were derived using the van Hees algorithm implemented in the R package GGIR, including only participants with at least four valid nights. Beyond average nighttime sleep duration, sleep IIV was defined as the standard deviation of nocturnal sleep onset, duration, and wake time. Children’s narrative comprehension was assessed using the Story Comprehension subtest of the Hong Kong Test of Preschool Oral Language. Hierarchical regression models were conducted in blocks, with age, gender, nonverbal intelligence, and socioeconomic status entered first as covariates, followed by sleep duration, sleep-IIV indices, and sleep duration × IIV interaction terms. Subsequent path analyses evaluated whether working memory (Digit Span Backward) statistically mediated these associations. Results: Path analyses and hierarchical regressions revealed three main findings. First, longer sleep duration was associated with better narrative comprehension indirectly via enhanced verbal working memory. Second, wake time IIV interacted with sleep duration (β = .22, p = .034); simple slopes revealed a potential buffering pattern where higher wake time IIV was associated with poorer narrative comprehension only among children with short sleep duration, whereas this negative association was neutralized for those with long sleep duration. Third, sleep duration IIV showed an independent negative main effect (β = -.26, p = .033) on narrative comprehension. Conclusion: Our findings suggest mechanisms by which distinct sleep dimensions relate to narrative comprehension: (1) sleep duration acts as a foundational resource that supports working memory for complex narrative processing; (2) sufficient sleep duration also provides neurocognitive resilience, buffering against the detrimental effects of irregular wake schedules; and (3) sleep duration instability may represent an independent risk marker for higher-order language development beyond average sleep duration. Overall, adequate sleep duration may serve as a basis for cognitive resources that, together with stable sleep duration and wake schedules, support early higher-order language development.
Topic Areas: Language Development/Acquisition,