Sleep, Circadian Rhythm, and Glucose Regulation in Adults Post-Coronary Artery Bypass

Disruption of sleep, circadian rhythm (24-hour sleep-wake cycle) and glucoregulation represent a major problem for individuals undergoing coronary artery bypass graft (CABG) surgery and may result in prolonged length of stay, postoperative convalescence, cardiovascular morbidity, and impaired immune function.3 Cardiovascular disease is the number one cause of mortality4 and CABG and valvular surgeries are the most commonly performed cardiac surgery with an annual rate of over 680,000 in the United States.5 Individuals post-CABG are cared for in the intensive care unit (ICU) environment where exposure to fluorescent lighting, frequent noise, and a fragmented sleep-wake cycle contributes to circadian and glucose disruption.12 Further, the degree to which the circadian rhythm and glucoregulation are altered from baseline in individuals post-CABG is largely unknown. Therefore, the purpose of this descriptive study is to examine sleep and circadian rhythm characteristics and the relationships between sleep, circadian rhythm, and glucoregulation among adults in the intensive care unit postoperative CABG/VR surgery. In Aim 1, we will determine between- and within-person associations of sleep, circadian rhythm and glucoregulation associations among 30 adults post-coronary artery bypass graft with or without valvular surgery. Sleep and circadian characteristics will be described through the timing of behavioral (actigraphy) measures. In Aim 2, we will compare sleep, circadian rhythm characteristics, and glucoregulation among post-coronary artery bypass with or without valvular surgery based on clinical characteristics of operative time, intensive care and hospital length of stay and discharge disposition. Our central hypothesis is that higher sleep and circadian disruption are associated with poorer glucoregulation and that there are sleep, circadian, and glucoregulation among individuals post-CABG/VR. The proposed F31 study and training plan will provide a strong foundation in sleep and circadian rhythm health. Promoting sleep and circadian rhythm stability post-surgery through behavioral modifications may improve glucoregulation by reducing insulin resistance, improving insulin sensitivity, and other short- and long-term postoperative outcomes in a population where such clinical gains may otherwise be difficult to achieve. This study will provide information on the impact on glucose in the setting of sleep and circadian rhythm disruption in coronary artery post-operative outcomes in the ICU where it is critical to optimize glucoregulation. Additionally, these results will provide preliminary evidence to inform future longitudinal and intervention studies to improve glucoregulation and postoperative outcomes in this understudied population.