Effects of behavioral interventions on psychological and biometric measures of well-being in young adults: results of a 14-week, four-arm, randomized, controlled trial

Background: College students are at increased risk of poor mental health and well-being as well as poor sleep. There is an ongoing need for accessible interventions for young adults in this important period of transition. Nature-based interventions have been proposed as scalable strategies to reduce stress and improve health, yet few randomized controlled trials have assessed their longitudinal effects on both mental health and physiological functioning.Methods: We conducted a 14-week randomized controlled trial conducted from January 21, 2023, to May 5, 2023 among college students at a single university (N = 379). Participants were randomized to the control group or one of three interventions: physical activity, nature experiences, or group therapy. Each intervention offered weekly group activities and prompted intervention-specific individual activity suggestions. The physical activity group completed weekly exercise routines; the nature experiences group spent quality time in nature each week; and the therapy group engaged in skill-based group therapy. Individual activities were scheduled through the study app. Weekly self-reported health measures included the Depression, Anxiety, and Stress Scale (DASS-21), the Perceived Stress Scale (PSS), and the Warwick-Edinburgh Mental Well-being Scale (WEMWBS). Physiological sleep measures were continuously recorded via Oura Rings. We used an intention-to-treat analysis, including participants that attended at least one group activity, and mixed-effects models to assess intervention effects over time. To explore potential mechanisms, mediation analyses were conducted to assess whether reductions in self-reported health measures mediated the effects of interventions on sleep measures.Findings: A total of 379 participants were included in the intention-to-treat analysis based on initial randomization. The mean (SD) age was 18.4 (0.5) years, with 229 (67.8%) being female and 295 (87.3%) identifying as white. Notably, 228 (67.5%) reported a mental health diagnosis at baseline. The Nature group demonstrated significant improvements in stress (β = –1.507, p = .047), well-being (WEMWBS × Week: β = 0.107, p = .039), and HRV (β = 9.13, p = .037). Mediation analyses suggest that stress reduction partially mediated the effect of nature on HRV and well-being. Gender and mental health history were significant covariates, with males reporting more favorable outcomes compared to non-males, and those with prior mental health conditions reporting poorer outcomes.Interpretation: Results support the potential utility of behavioral interventions on reported and biometric measures of well-being with particular promise in nature-based programs that are low-cost and scalable. Participants in the nature exposure group showed improvements in both subjective and objective health outcomes. Improvements in sleep estimates were partly explained by reductions in perceived stress and improved well-being, supporting the inclusion of nature-based strategies in public mental health planning. Further research is needed to understand the broader implications of these findings for promoting well-being among college students during their transition to higher education.