Relationship Between Subtypes of Restricted and Repetitive Behaviors in Sleep Disturbance in Autism Spectrum Disorder

Background: Sleep disturbance is common in children with autism spectrum disorder (ASD) and behavioral contributors often exist. We examined the association of two types of restricted and repetitive behaviors (RRBs), repetitive sensory motor (RSM) and insistence on sameness (IS), with sleep problems in children with ASD.

Objectives: The study aimed to detect RSM and IS behaviors within a registry of children with ASD.  We sought to understand the association of latent RSM and IS variables with parent reported sleep disturbance. We hypothesized that higher rates of RSM would be associated with more sleep disturbance and that higher rates of IS would be associated with better sleep. We controlled for prevalent markers of sleep disturbance in ASD, including age, cognition, and total autism severity.

Methods: Data were extracted from the Autism Speaks Autism Treatment Network (AS-ATN) registry. Registry participants included children ages 2-17 who met classification for an ASD based on the Autism Diagnostic Observation Schedule (ADOS) and DSM-IV-TR. Measures included the ADOS, Autism Diagnostic Interview-Revised (ADI-R), Vineland, and the Children’s Sleep Habits Questionnaire (CSHQ). Standardized intelligence scales also were administered. The final dataset included 339 children whose parents had completed the ADI-R and CSHQ. As previous exploratory analyses support the construct validity of RSM and IS, a confirmatory factor analysis (CFA) was conducted for selected ADI-R RRB items. RSM and IS severity scores were calculated from the individual items and the mean score for each scale was computed. Total sleep problems from the CSHQ was regressed against RSM and IS severity scores, while controlling for previously determined correlates of sleep disturbance, including age, IQ, and measures of overall autism severity (i.e.,  communication scores from the Vineland and social affect totals from the ADOS). Potential covariates were included in the model if they were significant at the 0.15 alpha level.

Results: CFA of selected items from the ADI-R detected RSM and IS in this dataset. The proposed model fit well (CFI = 0.90, SRMR =.06, RMSEA = .05). All factor loadings were statistically significant (t values >3, p <.05; Table 1). IS was significantly associated with total sleep problems after controlling for other known markers. When controlling for communication ability, total sleep problems increased by about 2.3 units for each unit increase in IS. For each unit increase in RSM, total sleep problems increased by about three points. This association was no longer significant when controlling for communication skills. Comprehensive results, including association of RSM and IS to CSHQ bedtime resistance and sleep onset scales are presented in Table 2.

Conclusions: Our findings yield validity to previous research indicating that RRBs can be parsed into factors, including RSM and IS. To the best of our knowledge this was the first study to assess health behavior, specifically sleep disturbance, in relation to these constructs.  The association of RSM, IS, sleep problems, and developmental functioning was complex and further study is warranted. Better understanding of the behavioral challenges of children with ASD at nighttime may contribute to better sleep and improved daytime functioning.