Sleep quality relates to language impairment in children with autism spectrum disorder without intellectual disability

Objectives: This study aimed to identify sleep quality profiles of children with autism spectrum disorder (ASD), to compare these profiles with those of typically developing (TD) children, and to verify whether there are differences between them in terms of language skills. Methods: We evaluated the sleep quality and language skills of 47 children with ASD without intellectual disability (ID) and 32 children with TD. Using a hierarchical cluster analysis, we identified two sleep quality ASD profiles (poor and good). We then performed a series of MANCOVAs and ANOVAs to compare the sleep quality and language skills of the two ASD clusters and the TD group. Results: A main group effect (TD, "poor" cluster, and "good" cluster) was found in the total sleep quality and all its dimensions. Significant differences were revealed between the "good" and "poor" clusters in the total structural language score (F1,46 =10.75, p < 0.001) and three of its subscales (speech: F1,46 = 9.19, p < 0.001; syntax, F1,46 = 8.61, p = 0.001; coherence: F1,46 = 11.36, p < 0.001); the total pragmatic language score (F1,46 = 7.00, p = 0.001) and three of its subscales (inappropriate initiation: F1,46 = 8.02, p = 0.001; use of context: F1,46 = 8.07, p = 0.001; nonverbal communication: F1,46 = 7.35, p = 0.001); and the social relations score (F1,46 = 9.97, p = 0.003). Conclusions: Sleep quality in children with ASD (especially a subgroup) is worse than in children with TD. There is an association between sleep quality and language skills, both at the pragmatic and structural levels.