Daily positive events and inflammation: Findings from the National Study of Daily Experiences

Background: Inflammation is implicated in the development of chronic diseases and increases the risk of mortality. People who experience more daily stressors than others have higher levels of inflammation, but it is unknown whether daily positive events are linked to inflammation. Objective: To examine the association of daily positive events with 3 inflammatory markers, interleukin-6 (IL-6), C-reactive protein (CRP), and fibrinogen. Method: A cross-sectional sample of 969 adults aged 35-86 from the Midlife in the United States Study completed telephone interviews for 8 consecutive evenings. Participants reported positive experiences that occurred over the past 24. h. Blood samples were obtained at a separate clinic visit and later assayed for inflammatory markers. Regression analyses evaluated the frequency of daily positive events (defined as the percent of study days with at least 1 positive event) as a predictor of each inflammatory marker. Covariates included information on demographics, physical health, depressive symptoms, dispositional and behavioral factors, and daily positive and negative affect. Results: On average, participants experienced positive events on 73% of days (SD = 27%). The frequency of daily positive events was associated with lower IL-6 (p < 0.001) and CRP (p = 0.02) in the overall sample, and lower fibrinogen among women (p = 0.01). The association remained for IL-6 in the fully adjusted model, but was no longer significant for CRP and fibrinogen after controlling for household income and race. Effects were more pronounced for participants in the lowest quartile of positive event frequency than for those in the top 3 quartiles, suggesting that lack of positivity in daily life may be particularly consequential for inflammation. Furthermore, interpersonal positive events were more predictive of lower IL-6 overall and lower fibrinogen in women than non-interpersonal positive events. Conclusion: Daily positive events may serve a protective role against inflammation.