The Bi-Directional Association between Sleep Problems and Autism Spectrum Disorder Symptoms: A Population-Based Cohort Study

Background:

Sleep difficulties are prevalent in children with Autism Spectrum Disorder (ASD), occurring in 40-80% of cases across all ages. The association between sleep problems and ASD can be of two forms. First, sleep problems may precede and worsen the behavioural outcome of ASD. Second, sleep problems may occur as a consequence of the underlying disorder. Because longitudinal studies are lacking, the temporal nature of the association between sleep problems and ASD is unclear.

Objectives:

Our aim is to clarify whether sleep problems precede and worsen autistic traits and ASD or occur as a consequence of the disorder. This enables us to gain more insight in the course of sleep problems in children with ASD over time which can be beneficial for parents and for clinical practice.

Methods:

Repeated mother-reported sleep measures were available at 1.5, 3, 6, and 9 years of age in 5151 children participating in the Generation R Study, a large prospective birth cohort in the Netherlands. Autistic traits were reported by the mother using the Pervasive Developmental Problems score (PDP) of the Child Behavior Checklist (CBCL) at 1.5, 3, and 6 years and the Social Responsiveness Scale (SRS) at 6 years. This cohort included 81 children diagnosed with ASD by a clinician who we compared with the rest of the sample.

Results:

Sleep problems in early childhood were prospectively associated with a higher SRS score, but not when correcting for baseline PDP score. By contrast, a higher SRS score and an ASD diagnosis were associated with more sleep problems at later ages, even when adjusting for baseline sleep problems. Likewise, a trajectory of increasing sleep problems was associated with ASD.

Conclusions:

Sleep problems and ASD are not bidirectionally associated. Sleep problems do not precede and worsen autistic behaviour, but rather co-occur with Autistic traits in early childhood. Yet, as supported by our trajectory analyses, the severity and frequency of sleep problems decreases in typically developing children, whereas sleep problems worsen over time in children with ASD. This strongly suggests that the pathology underlying ASD on the behavioural sequelae, determines the development of sleep problems. A possible mechanism for why sleep problems in children with ASD persist could be that social problems associated with ASD may worsen the day-night rhythm in these children and play a crucial role in the development of sleep problems. Socialization of day-night rhythm by parents, such as bed time routines, night time rituals, and family regularity, are important in young children as they can act as social zeitgebers and thereby contribute to the development of a healthy sleep pattern and the prevention of the occurrence of sleep problems. Children with ASD have difficulty to adequately respond to the social zeitgebers and therefore may struggle to develop a healthy sleep pattern. More research is needed to unravel the socialization of day-night rhythm in children with ASD and the linkage with the development of sleep problems. Future studies should emphasize bed time routines and family regularity when investigating children with ASD and sleep problems.