Sedentary screen time (SST) is the most common discretionary activity among all US age and race/ethnic groups. SST is associated with poor health outcomes, including cardiovascular disease (CVD). Recreational SST (rSST) is 2-3X more detrimental to health than other forms of sedentary behavior (e.g., workplace sitting, traveling). Elucidating the mechanisms that lead to elevated harm resulting from rSST is critical. Impact of the COVID-19 pandemic to increase rSST amplifies the urgency of understanding rSST-related mechanisms that lead to detrimental health outcomes. Previous SST studies are limited in scope of intervention and outcomes. There are vital gaps in knowledge about how rSST and rSST-associated behaviors lead to increased CVD risk. Interventions applied in ecologically valid, real-world settings are urgently needed to develop the most potent interventions that address and attenuate critical mechanistic pathways that mediate rSST-associated health risks. WatchWell is a pilot study designed to achieve three important goals that will support our obtaining funding for this research and is responsive to reviewer comments on our previously submitted NIH/NHLBI P01 Program Project: 1) demonstrate feasibility and participant acceptability of study design 2) demonstrate participant acceptability of measurement devices; 3) generate preliminary data to estimate outcome effect sizes.
In the course of WatchWell, the team of investigators will intervene on 3 behavioral mechanisms that are likely primary drivers of dSST CVD risk based on their prominent co-occurrence with rSST and individual contributions to CVD risk: blue light at night, nighttime food intake and prolonged evening sitting time. The investigators hypothesize that these 3 behavioral mechanisms impact CVD risk via downstream biological mechanisms including diurnal sleep/wake and body temperature rhythms, glucose metabolism, and autonomic balance (including heart rate variability, HRV). These biological mechanisms have not been assessed concurrently nor in the real-time, real-world context of rSST-related behaviors.
For this WorkWell pilot, the team of investigators will test 2 of the 3 behavioral mechanisms compared to the baseline control condition per participant using a 3-condition randomized controlled crossover design. \[In the full trial to be resubmitted to the NIH, we will conduct a 4-condition crossover RCT, testing all 3 behavioral mechanisms compared to the baseline control condition per participant.\] The investigators will recruit adults with overweight and at least 2 criteria of the metabolic syndrome (goal of N=18 completers, up to 30 enrollees total), who have elevated CVD risk. Impact. Recreational SST is a highly prevalent, modifiable risk factor for CVD. WorkWell will be the first to intervene on rSST-associated evening/nighttime blue light, food intake, and prolonged sitting in a real-world setting and to concurrently measure downstream CVD-related biological mechanisms. The WorkWell study design is informed by and will contribute to the translational application of circadian biology.
Aim 1. Assess the study feasibility and participant acceptability of delivering three behavioral strategies (avoiding dietary intake after 8p; blocking blue-light exposure after 8p; and breaking up prolonged sitting with standing after 5p) to reduce negative health exposures associated with rSST over two-week conditions in a randomized crossover study design.
Aim 2. Assess protocol compliance and participant acceptability of a suite of wearable sensors and home-based technologies during the feasibility trial.
Aim 3. Assess the preliminary efficacy and estimate effect size of the three behavioral strategies for improving postprandial glucose metabolism (primary focus on post-dinner meal, postprandial period), related 24-hr behaviors (sleep, other sedentary time, physical activity), heart rate variability, and circadian rhythms (sleep/wake activity rhythms, surface body temperature rhythms).
