Wings of recovery : integrating behavior change and design science in digital work stress interventions

Background: Work-related stress is a prevalent risk factor for physical and mental health problems. Digital Behavior Change Interventions (DBCIs) have emerged as promising tools to address this issue by providing accessible and scalable support to employees in need. These interventions can help individuals develop a habit of recovery that offsets the negative effects of stress, thus reducing the risk of long-term health issues. However, designing effective tools remains a complex challenge requiring the integration of diverse research domains. To be successful, a DBCI must promote optimal recovery behaviors to alleviate stress reactions, facilitate the behavior change process required to form these habits, and sustain user engagement during the intervention period. Aim: This thesis aims to advance our understanding of how to design and evaluate digital work stress interventions. It investigates three core aspects of DBCIs: (1) identifying the target behaviors the intervention aims to promote, (2) understanding the mechanisms that facilitate the behavior change process, and (3) how to deliver interventions in a digital format that sustain user engagement. By exploring each of these aspects and their integration, this thesis offers theoretical insight, practical design considerations, and recommended guidelines for intervention development. Methods: The overarching methodological approach mirrors the iterative, mixed-methods, and pragmatic approach of design science research. Through the development and testing of DIARY, a digital work stress intervention, this research contributes both theoretical understanding and practical insights for DBCI design. Quantitative analyses are used to model predictors of mental health and engagement measures. Complementary qualitative methods, such as thematic analysis of semi-structured interviews, provide depth and contextual understanding. The thesis comprises four studies. Study I was a mixed methods study examining engagement patterns to identify factors influencing uptake and adherence. Study II utilized a factorial experimental design to investigate the effects of intervention components on mental health outcomes. Informed by initial findings, Study III evaluated a refined version of DIARY to assess the feasibility of the updated intervention design. This pilot study tested a new interface, an expanded set of recovery strategies, and revised measurement instruments in preparation for larger-scale trials. Study IV (preliminary results) reviewed and analyzed existing digital interventions, using a narrative synthesis to identify key design features contributing to engagement and behavior change. Findings: The thesis identifies key design considerations across the three investigated aspects. Study I found that the time and effort required to use the intervention is a critical predictor of engagement: quick and smooth interactions proved essential for promoting uptake and adherence. Regular notifications were effective for reminding participants to engage, also supporting a habit of using the intervention. Additionally, having a pre-existing internal motivation to engage with the intervention was observed in participants with higher adherence. Study II identified that a combination of self-reflection and actionable recovery strategies had the strongest positive impact on stress-related health outcomes. Notably, a synergistic effect was observed in that experimental conditions containing both components yielded the largest effect sizes. Self-reflection may support insight into recovery needs, while the provision of strategies offers users concrete tools to address these effectively. Study III provided additional evidence that time-efficient and easy interactions are important drivers of engagement. The new intervention version with improved technical stability and an updated interface showed promising adherence and app engagement ratings. Methodologically, this study highlighted the necessity of using proximal measures of behavior change (e.g., frequency of recovery activities) rather than relying on distal mental health effects for evaluation. Study IV (preliminary results) contrasts these findings with the broader literature. Beyond corroborating the value of reminders, self-monitoring, and feedback features, this study highlights the potential utility of personalization, goal setting, rewards, and social support in DBCI for work stress. Furthermore, this study suggests that effective design features should be deliberately developed to instantiate psychological principles known to influence behavior and engagement. Conclusion: Digital work stress interventions require a holistic design approach that balances user-centered design practices with evidence-based psychological knowledge. This thesis demonstrates that engagement is in part driven by internal motivation and minimal friction in intervention interactions. Regular reminders support adherence and aid the habit formation process by providing consistent cues for behavior repetition. Optimal target behaviors combine self-reflection that helps users become aware of their internal state with a diverse repertoire of strategies that allows them to choose the activities that match their needs and preferences. By viewing digital features as direct translations of psychological principles, researchers and designers can create potent interventions that successfully drive both user engagement and meaningful behavioral change. List of scientific papers I. Kowalski, L., Finnes, A., Koch, S., & Bujacz, A. (2024). User engagement with organizational mHealth stress management intervention-A mixed methods study. Internet Interventions, 35, 100704. https://doi.org/10.1016/j.invent.2023.100704 II. Kowalski, L., Finnes, A., Koch, S., & Bujacz, A. (2025). Optimizing Intervention Components of a Preventive Stress Management mHealth Intervention for Health Care Workers: Experimental Factorial Study. JMIR Formative Research, 9, e71032. https://doi.org/10.2196/71032 III. Kowalski, L., Finnes, A., Koch, S., Stenling, A., & Bujacz, A. (2024). Recovery at your fingertips: pilot study of an mHealth intervention for work-related stress among nursing students. BMC Digital Health, 2(1), 64. https://doi.org/10.1186/s44247-024-00120-w Preliminary Results IV. Kowalski, L., Finnes, A., Koch, S., & Bujacz, A. Key Design Considerations for Digital Work Stress Interventions: Content Analysis & Narrative Synthesis. [Manuscript]