Night Shift Work, On-shift Napping, and Endothelial Function: A Pilot Study

Cardiovascular disease (CVD) and CVD risk factors such as high blood pressure (BP) are disproportionately higher among night shift workers, including those who work in public safety and healthcare. Risk of CVD events such as myocardial infarction and stroke are higher among shift workers than non-shift workers. Risk of atrial fibrillation is 1.22 times greater (95%CI 1.02, 1.45) among individuals that work 3-to-8 night shifts per month versus non-shift workers. A comprehensive explanation for why shift workers, especially night shift workers, are at greater risk of CVD is not yet available. However, some research suggests that night shift workers experience repeated exposure to sleep deprivation, which impacts normal patterns in BP and endothelial function. Endothelial dysfunction and disruption of normal BP patterns are independently linked to numerous indicators of CVD, including cardiac-related mortality. The purpose of this pilot study is to assess feasibility of collecting data germane to key indicators of cardiovascular health (i.e., ambulatory blood pressure) repeatedly during a simulated night shift protocol. Investigators propose a laboratory-based pilot study whereby participants (volunteers) complete two conditions. Condition one will include a 12-hour simulated night shift in our lab with no napping. Condition two will involve a 12-hour simulated night shift in our lab with a 45 minute nap at 0200 hours. Participants will be asked to wear monitoring devices for approximately 48 total hours with the last 12 hours of monitoring (from 1900 to 0700) to be in our lab. Aim 1: Assess the feasibility of collecting ambulatory BP measures (ABPM) and indicators of endothelial function at multiple time points prior to, during, and after simulated night shift work. The primary outcome measure will be the number of participants for which at least 70% of required ambulatory BP measures were collected. A result of at least 10 participants/subjects will be considered feasible. Aim 2: Characterize the impact of simulated night shift work and on-shift napping on BP dipping and endothelial function. Secondary endpoints include quantifying descriptive statistics (e.g., means and standard deviations) for BP dipping and endothelial function.