Background. Cardiac events are the leading cause of death among firefighters and occur while on-duty at analarmingly high rate. Short disrupted sleep is a major modifiable risk factor for cardiovascular disease (CVD)and up to 40% of firefighters experience sufficiently severe sleep disruption to screen positive for sleepdisorders. Cognitive behavioral therapy for insomnia (CBTi) is well-established as efficacious and effectivewithin health care settings. However the effectiveness of CBTi-informed sleep health coaching and sleephealth promotion in workplace settings and among firefighters specifically is largely unknown. Theory-drivenresearch is required to address this research-to-practice gap and also identify facilitators to and barriers ofintervention implementation in this high-risk population.Goal. The primary objective of this proposal is to examine whether a scalable CBTi-informed interventionfirefighter sleep health coaching (ffSHC) improves sleep disturbances when implemented in a real-world high-demand work environment.Methods. This study proposes to conduct a stepped wedge cluster randomized controlled trial in order toexamine the effectiveness of an evidence-based sleep health coaching intervention delivered to 400 careerfirefighters across 20 fire departments (Aim 1). The primary outcomes are (a) the pragmatic PROMIS SleepDisturbances questionnaire and (b) the multidimensional sleep health index derived from actigraphy.Secondary and tertiary outcomes include: sleep related impairment sleep continuity blood pressure heartrate and long-term clinic-assessments of cholesterol body mass index and blood pressure. To advanceimplementation science this project will employ the Integrated Promotion Action on Research Implementationin Health Services (iPARIHS) framework to guide a mixed methods formative evaluation (Aim 2a) ofintervention adaptations and implementation strategies. A theory-based process evaluation (Aim 2b) isembedded within the clinical trial to explore combinations of factors that promote agency-level implementationand to inform future implementation research in public safety settings.Significance and Innovation. This research will accelerate the translation of sleep health intervention toworkplace wellness and advance implementation science through the application of the iPARIHS framework.The use of sleep health coaches is innovative and models how programs may expand reach to address theglobal problem of insufficient sleep. The long-term goal of this research is to provide critical knowledge thatfacilitates the widespread implementation dissemination and sustained utilization of sleep health intervention topromote continuous sufficient sleep and ultimately mitigate CVD risk. Achievement of study goals will improve thehealth and wellness of firefighters a population whose health is vital to assuring public safety and supportingcommunity resiliency.