METHOD: A cross-sectional study was conducted at Hospital Tunku Azizah, Kuala Lumpur, Malaysia, from June 2020 to December 2020. Children between 2 and 5 years old, diagnosed with ASD based on the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) criteria, were recruited. Two parent-reported questionnaires, the Children's Sleep Habits Questionnaire (CSHQ) and the Child Behaviour Checklist (CBCL/1.5-5), were used to assess sleep and behaviour, respectively. Children were classified as good sleepers (CSHQ score <41) and poor sleepers (CSHQ score ≥41). Poor sleepers were further categorised into those with mild or moderate to severe sleep problems (based on the 75th percentile CSHQ score). The CBCL/1.5-5 raw scores were converted to standardise T-scores, yielding scores of three summary scales (internalising, externalising and total problems).

RESULTS: A total of 134 children participated in this study. Their mean age was 42.23 ± 9.95 months, and 81.3% were males. Mean CSHQ score was 49.77 ± 6.90, and 93.3% were poor sleepers. Internalising, externalising and total problems scores were significantly higher in poor sleepers (62, 59 and 62, respectively) compared to good sleepers (56, 47 and 51, respectively). Children with moderate to severe sleep problems had clinical scores of internalising (median 65) and externalising (median 65) problems, as compared to mild sleep problems (median internalising score 61, median externalising score 57).