The Influence of Daily Stress on Sedentary Behavior: Group and Person (N of 1) Level Results of a 1-Year Observational Study.

Objective: The purpose of this study, which used mobile technologies to continuously collect data for 1 year, was to examine the association of psychological stress with objectively measured sedentary behavior in adults at both the group (e.g., nomothetic approach) and individual (e.g., idiographic approach) level.

Methods: Data were collected in an observational study of healthy adults (n = 79) residing in the New York City metro area who were studied for 365 days from 2014 to 2015. Sedentary behavior was objectively measured via accelerometry. A smartphone-based electronic diary was used to assess level of stress ("Overall, how stressful was your day?" 0-10 scale) and sources of stress.

Results: The end-of-day stress rating was not associated with total sedentary time (B = -1.34, p = .767) at the group level. When specific sources of stress were evaluated at the group level, argument-related stress was associated with increased sedentariness, whereas running late- and work-related stress were associated with decreased sedentariness. There was a substantial degree of interindividual variability in the relationship of stress with sedentary behavior. Both the level and sources of stress were associated with increased sedentariness for some, decreased sedentariness for others, and had no effect for many (within-person variance p < .001).

Conclusions: These findings suggest that the influence of stress on sedentary behavior varies by source of stress and from person to person. A precision medicine approach may be warranted to target reductions in sedentary time, although further studies are needed to confirm the observed findings in light of study limitations including a small sample size and enrollment of participants from a single, urban metropolitan area.