Background Numerous studies have shown that sleep disturbances are common in children with autism spectrum disorder. However, to the best of the authors’ knowledge, there is no local study to date looking at the prevalence of sleep disturbances in children with autism spectrum disorder and its impact on the child’s behaviour.

Objectives The primary aim of this study was to determine the prevalence of sleep disturbances among children with autism spectrum disorder aged between 2 to 5 years old. The secondary aim was to determine the relationship between sleep disturbances and behavioral problems in these children.

Methods This study was conducted at a tertiary center from June 2020 to December 2020. Children between 2 to 5 years of age, who were diagnosed with autism spectrum disorder based on the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) criteria by a developmental paediatrician, were enrolled in this study during their routine clinic appointment. Guardians were given two questionnaires, the Children’s Sleep Habits Questionnaire (CSHQ) and Child Behavior Checklist (CBCL/1.5–5), to be answered. Children who had refractory epilepsy, chromosomal abnormality and absence of a guardian to answer the questionnaires were excluded.

Results 139 children were recruited in the study. 5 children dropped out, giving a sample size of 134. The mean age (SD) was 42.23 (9.95) months. There were 109 males (81.3%) and 25 females (18.7%). Children were classified as good sleepers (CSHQ score of less than 41) and poor sleepers (CSHQ score of greater than 41). 9 (6.7%) children were good sleepers and 125 (93.3%) were classified as poor sleepers. The mean score (SD) on the CSHQ was 49.77 (6.90). The internalizing, externalizing and total problems T score, as measured by the Child Behavior Checklist, was significantly higher in the poor sleeper group compared to the good sleeper group.

Conclusions The prevalence of sleep disturbances in the study population is high at 93.3%.

These children tend to have a higher internalizing, externalizing and total problems on the CBCL, suggesting poor sleep negatively affects the behavioral outcome in children with autism spectrum disorder.