0003 Sleep and Circadian Disruption Induced by Simulated Night Shift Work Impair Cardiometabolic Outcomes in Healthy Adults

Abstract

Abstract Introduction People who work evening, night or rotating shifts make up 20% of the US workforce and have a heightened risk for Type 2 diabetes (T2D) and cardiovascular disease (CVD) compared to people who work days, possibly due to repeated bouts of sleep and circadian disruption. However, the mechanism(s) by which sleep and circadian disruption impair cardiometabolic health are unclear. We therefore investigated the impact of acute circadian misalignment on factors related to cardiometabolic health including interstitial glucose concentration, glucose tolerance, resting systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR). Methods Ten healthy adults (6F, 25.0±4.5y, BMI: 22.0±2.2kg/m2; mean±SD) participated in an ongoing 6d inpatient simulated night shift protocol to induce sleep and circadian disruption. Participants lived at the Sleep and Metabolism Laboratory for 2d to simulate day shift work followed by 2d of simulated night shift work. Continuous interstitial glucose monitoring was conducted throughout the study (FreeStyle Libre Pro; Abbott, Alameda, CA, USA). BP and HR were assessed 30 minutes after waketime (Omron HEM-FL31; Omron Healthcare, Kyoto, JP) followed by an oral glucose tolerance tests (OGTT) conducted 1.5h after waketime in both conditions. Results Simulated night shift work was associated with significantly higher interstitial glucose area under the curve (AUC) in response to an identical first meal after waking (18,299±1412 v 14,606±2035 [mg/dl]*min; p=0.009; mean±SEM) as well as plasma glucose AUC during the OGTT (23,239±2574 v 18,776±1832; p=0.002) compared to simulated day work. Furthermore, simulated night shift work was associated with a significant increase in resting DBP (75±3 v 66±2; p=0.017) compared to day work. No changes were observed in resting SBP (p=0.40) or HR (p=0.11) between conditions. Conclusion Sleep and circadian disruption induced by simulated night shift work appear to impair markers of cardiometabolic health, even in healthy, lean adults. Night shift work is largely unavoidable in modern society, thus is it critical to identify strategies or countermeasures to prevent the impact of circadian misalignment on T2D and CVD risk in a large portion of the population. Support (if any) This project was supported in part by R01DK125653 & F31HL165883.