Good Nights Sleep Program: A Randomized Clinical Trial to Improve Children's and Parents' Sleep - Sleep is vital to physical and mental well-being, so it is imperative that research communities help individuals and families sleep longer. Low-income children and parents face obstacles to achieving optimal sleep. Family stress impedes evening behaviors that support sleep hygiene practices, and environmental factors like noise and light exposure reduce sleep quality. It is not surprising, then, that many low-income children and parents experience short, poor-quality, and irregular sleep. Sleep disturbances, in turn, contribute to broader health problems such as cognitive dysfunction, cardiovascular disease, and depression. Accordingly, basic research converges on two potential targets of intervention to improve sleep health for individuals within low-income families: sleep hygiene practices and sleep environments. The objective of this project is to conduct a randomized clinical trial (RCT) designed to improve sleep hygiene practices and sleep environments and, subsequently, sleep health for children and parents within lowincome families. This project addresses significant problems in that many sleep interventions are prescriptive, addressing sleep problems that are applied in the same way to all individuals, while often ignoring the nonindependence of sleep hygiene practices and sleep environments within parent-child dyads. Importantly, the barriers to adequate sleep vary between parents and children as well as between families. This innovative intervention is adapted to the needs of low-income families: it required a minimal amount of contact time, it targets only the sleep needs that each participant experiences, it utilizes social support within parent-child dyads, and it is delivered within participants’ communities. It also builds on established, evidence-based health behavior change strategies to collaboratively select and track individual- and parentchild dyad-level sleep health goals. The research design is a rigorous RCT (two-arm; experimental and attention control) with repeated measures. Recognizing that repeated measures are nested within individuals and individuals are nested within parent-child dyads, the specific aims are to: (1) evaluate the effects of the intervention on objective and subjective assessments of sleep health; (2) evaluate the effects of the intervention on sleep hygiene practices and sleep environments and such changes as mediators / mechanisms of the effects of the intervention on sleep health; and (3) evaluate the effects of the intervention on cognitive, physical, and mental well-being, considering change in sleep health as a mediator / mechanism of intervention effects on these health outcomes at intraindividual, interindividual, and inter-dyad levels of analysis. As defined by the NIH Stage Model for Behavioral Intervention Development, the present project represents the transition between the recently completed Stage 1 (NCT06249217) to Stage 2 of the development of this behavioral intervention. Consistent with a relevant program announcement (PAR-24- 330), the long-term goal of this project is to refine and disseminate an efficacious and effective behavioral intervention to improve sleep health.