PROJECT SUMMARY People who work evening, night or rotating shifts (i.e. “nonstandard” work hours) make up 20% of the US workforce, have a 17% higher risk of cardiovascular disease (CVD) compared to people who work days. Sleep and circadian misalignment are two mechanism suggested to increases the risk of CVD in people who work non-standard hours, and is highly prevalent and often unavoidable in modern, 24-hour society (e.g. shift work, long work hours, jet lag, medical residency, emergency responders, military personnel, Daylight Savings Time changes, etc). Disruptions in sleep and circadian rhythms have been linked to insulin resistance, increased energy intake, weight gain, and increased total body, abdominal and intrahepatic fat content, yet there have been limited attempts at identifying strategies or countermeasures to prevent the impact of such disruption on CVD risk in a sizeable proportion of the population. Therefore, our long-term goal is to identify and develop effective, behavioral countermeasures to combat the increased risk for metabolic diseases associated with sleep and circadian disruption when these behaviors are unavoidable. The overall objective for this project is to test the impact of time-restricted feeding to a 7h period in the day as a noninvasive countermeasure to the metabolic impairments associated with circadian misalignment. Our central hypothesis is that time-restricted feeding to the daytime period will prevent cardiovascular impairments during circadian misalignment compared to a condition where energy is consumed throughout the day and night. The rationale for the proposed project is that defining a non-invasive, scalable and feasible countermeasure to circadian misalignment could mitigate the risk of cardiovascular disease. To test our overall hypothesis, will use a randomized crossover study with a rigorous inpatient diet-, activity and light-controlled protocol in 32 healthy men and women. We will determine the impact of time- restricted feeding during circadian misalignment on 1) 24h blood pressure; and 2) vascular function. Findings from this study represent a critical advancement in the fields of translational circadian and metabolic physiology by identifying and testing a countermeasure to circadian misalignment. Achievement of our proposed aims could lead to the development of new intervention strategies for chronic disease prevention and management. The knowledge to be gained offers the potential to support cost-effective programs that may inform our healthcare approach to cardiovascular disease prevention in populations at risk for these diseases such as shift workers, individuals with sleep disorders and anyone who eats outside of daytime hours.