Stress reduction experiments in daily life: Scaling from the lab to the world.

Abstract

Paced breathing-longer exhalation than inhalation-can show short-term improvement of physiologic responses and affective well-being, though most studies have relied on narrow sample demographics, small samples, and control conditions that fail to address expectancy effects. We addressed these limitations through an app-based experiment where participants were randomly assigned to paced breathing or sham control (hand closure) conditions. We first validated the conditions in an online sample (N = 201; Study 1) and in a lab environment (N = 72; Study 2). In the primary app-based experiment, participants (N = 3,277; Study 3) completed 3 days of baseline assessments that included three check-ins each day in which we obtained heart rate and blood pressure responses using an optic sensor and assessed current stress and emotions. Participants were then randomly assigned to either the paced breathing or hand closure condition for the next 6 days. Relative to baseline days, both conditions were associated with increased positive emotions and perceived coping, and reduced blood pressure. Moreover, the increase in positive emotions and perceived coping was not evident among a comparison sample (N = 2,600) who completed check-ins but did not participate in either of the paced breathing or sham-control conditions. However, their blood pressure declined over time, suggesting that the continual monitoring of one's blood pressure may result in detectable decreases. Our results highlight the importance of designing experiments with appropriately matched control conditions and suggest that changes associated with techniques like paced breathing, in part, may stem from positive incidental features of the technique. Public Significance StatementStress can lead to hypertension and cardiovascular disease, one of the leading causes of death worldwide. Strategies that might reduce acute stress and increase positive emotions while improving cardiovascular health are as important as ever given the deleterious effects of depression and hypertension that plague our society. Several studies have shown that paced breathing is effective at improving emotions and cardiovascular health though many studies have relied on small samples and have not appropriately accounted for expectancy effects. Addressing these limitations, we found that the sham-control condition of opening and closing one's hand was associated with increased positive emotions and reduced blood pressure just as strongly as paced breathing during naturalistic contexts throughout the day. These data provide novel insights into the role of appropriately matched control conditions in exercises designed to improve emotional well-being and cardiovascular health in daily life.