Sleep profiles in children with autism spectrum disorder: a longitudinal perspective

2017-02-27T00:17:04Z (GMT) by Fletcher, Fay Ellen
Healthy sleep is a fundamental requirement for the developing child. Sleep problems are common throughout the school-age years however, where a variety of dysomnias (i.e., problems initiating and maintaining sleep) and parasomnias (e.g., sleep walking, night terrors) may prevent the acquisition of sufficient sleep. For children with Autism Spectrum Disorder (ASD), these problems exceed those of their typically developing (TD) peers. A plethora of neurobiological, psychological and behavioural factors have been shown to impact negatively on the sleep quality of children with ASD, which manifest in up to 80% of these children. The current thesis presents a series of papers which assess the nature of sleep in school-age children with and without ASD. Parent-report sleep profiles were complemented with fourteen nights of actigraphy data; a small wrist-watch device used to objectively measure sleep-wake profiles. These assessments were performed twice over a one year period to facilitate an examination of the trajectory of sleep over time. The impact of anxiety and bedtime routines on sleep profiles was also explored. Chapter 2 presents a systematic review of the magnitude of sleep problems in ASD. The review concludes that although sleep problems are considered a hallmark feature of ASD, past research is limited by heterogeneous study groups, a reliance on parent-report measures, and a scarcity of longitudinal research. Chapter 3 serves as a foundation paper, characterising the role of age, gender, and anxiety in the sleep profiles of TD children. Parent-report anxiety was significantly associated with concurrent parent-reported sleep problems. In contrast, parent-report anxiety was not significantly associated with concurrent ‘average’ actigraphy parameters, such as total sleep time, or sleep efficiency. However, anxiety was associated with increased night-to-night variability in actigraphy derived sleep schedules. Chapters 4 and 5 present cross-sectional and longitudinal comparisons of sleep in children with ASD and an age-matched subgroup of the TD cohort. Children with ASD were characterised by an increased severity across all aspects of parent-reported sleep difficulties, such as sleep onset delay, night wakings and bedtime resistance. When compared to actigraphy however, only the initiation of sleep differed between groups; namely children with ASD had a significantly longer sleep onset latency than TD children. It was also demonstrated for the first time, that the night-to-night variability of sleep in school-age children with ASD exceeds that of TD children. Evidently, several of the identified associations between parent-report measures were not mirrored by objective assessments, reinforcing the need for multi-rater and multi-modal assessment approaches. However, there is a lack of appropriate measures, and a reluctance to utilise self-report assessments, in children with ASD. Chapter 6 therefore presents the development and reliability of a novel self-report anxiety measure for children with and without ASD. It is proposed that with appropriate modifications, the utility of self-report measures may be increased. Therefore moving forward, self-report measures may be used to provide a unique insight into these relationships, alongside parent-report and objective measures. In both children with and without ASD, reductions in parent-reported sleep-problems were associated with reduced parent-report anxiety over time. Reductions in actigraphy derived sleep efficiency were associated with an increase in the presence of maladaptive activities (e.g., watching TV, playing video games), in the hour before bedtime. Collectively, these findings address several key limitations of past research to further characterise the nature and severity of sleep problems in children with ASD. The increased night-to-night variability of sleep in children with ASD, and the longitudinal associations between sleep and maladaptive bedtime routines provide important clinical implications. Specifically, the need for comprehensive and multi-modal sleep assessments is reinforced; including the identification of key psychological, behavioural and environmental factors known to impact negatively on sleep.