Sleep problems are very common in children with ADHD, with a prevalence rate as high as 73%, and often pose significant challenges and stress to the families. Sleep problems in ADHD children are strongly associated with the exacerbation of daytime symptoms, impaired physical health, and poor parental mental health. The present study is a randomised controlled trial to compare the effects of a parent-based sleep intervention for children with ADHD (aged 6-12). Eligible participants will be randomised to either intervention (two face-to-face consultation sessions and one follow-up phone call) or waiting-list control condition. Assessments will be conducted at pre-treatment (baseline), one-week after the intervention (post-treatment), and 3 months after the intervention.

Inclusion Criteria:

• Aged 6-12 years old;
• With a clinical diagnosis of ADHD (any subtype), as confirmed by the Diagnostic Interview Schedule for Children-version-IV (DISC-IV);
• With parent-reported insomnia (difficulty initiating sleep and/or maintaining sleep).

Exclusion Criteria:

• Children with a serious medical condition (e.g. severe cerebral palsy) or intellectual disability (IQ<70);
• Children with a neurological and/or medical condition that may lead to disordered sleep;
• Suspected clinical sleep disorders (e.g. obstructive sleep apnea, OSA) that may potentially contribute to a disruption in sleep continuity and quality, as assessed by the Children's Sleep Habits Questionnaire (CSHQ). If the child is suspected of a clinical sleep disorder, he/she will be referred to appropriate services;
• Children who are already receiving specialised help (behavioural intervention) for their sleep from a psychologist or at a specialized sleep clinic.