Just-in-time adaptive interventions to improve positive emotions in daily life: a randomized controlled experience sampling study

Background: Positive psychology interventions have been suggested to improve positive emotions and well-being, but effects are small and vary between individuals. To account for such heterogeneity, tailoring positive psychology interventions to individuals’ needs and context might be fruitful. Objective: The aim of this study is to investigate the feasibility and effectiveness of just-in-time adaptive interventions (JITAIs) inspired by positive psychology.Method: A sample of 142 students completed two experience sampling (ESM) periods (baseline and intervention) of 15 days each, with 5 assessments per day. During the intervention period, participants who were randomly assigned to the intervention group (N=72) received micro-interventions that were triggered when they reported relatively high or low positive emotion levels as compared to their positive emotions during the baseline ESM period. Participants answered questionnaires about their mental health (i.e., well-being, anhedonia, depressive symptoms) pre-intervention, post-intervention and at 3-month follow-up. Additionally, they provided narrative feedback on the intervention via open text boxes. Using dynamic structural equation models, repeated measures ANOVAs, and thematic analysis, we investigated whether JITAIs impacted momentary emotions and mental health at follow-up, respectively.Results: While thematic analyses revealed that JITAIs were generally positively evaluated, there were no significant quantitative effects of JITAIs on momentary positive or negative emotions, longer-term well-being, symptoms of depression, or anhedonia. However, the group who received micro-interventions showed a steeper rise in momentary positive emotions from the baseline to the intervention ESM period compared to the control group (β = 0.156, P = 0.028, 95%CI = 0.021-0.294). Conclusions: JITAIs are feasible, but in their current form not universally effective in improving momentary emotions or mental health at follow-up. Further research is necessary to better understand how and for whom core principles of JITAIs – specifically, the just-in-time and adaptive delivery of micro-interventions – should be implemented in practice.