Research Design. Investigators will use a RCT design, with a pragmatic trial approach, to evaluate the effectiveness of the intervention, adhering to CONSORT 2010 guidelines. Specifically, the investigators will conduct 4 individually randomized parallel-group RCTs, one for each NDD group (ASD, FASD, CP & ADHD), to assess whether the intervention improves children' sleep within each group at 3 months. Data collected at 6 months will assess the degree of maintenance of any initial treatment effects on child sleep, and the intervention's impact on child and caregiver psychosocial health.