Sleep disturbances represent a significant problem for many children on the autism spectrum and their families. Without intervention these sleep problems are unlikely to resolve and have been associated with a wide range of impacts on both child and family. Many factors have been recognised that can increase the complexity of delivering sleep interventions to families with children on the autism spectrum. It is therefore essential that interventions acknowledge these complexities and are tailored to meet the needs and values of individual families. This study investigated the feasibility of using a portable electronic device (PED) as part of a behavioural sleep intervention, informed by a Functional Behavioural Assessment (FBA). Outcomes were evaluated using four single-case studies, with AB designs, with children on the autism spectrum aged three to nine years (two female, two male). The PED intervention was perceived well by parents and while not being able to completely resolve sleep problems, may represent a useful and manageable steppingstone for families in facilitating sleep behaviour change, while reducing child resistance and distress. The findings also supported the use of a FBA-informed behavioural intervention to improve sleep in children on the autism spectrum. While complexity factors appeared to impact treatment adherence and outcomes in this study, the results also highlighted that improvements to sleep can be achieved, despite the presence of complexity.