Psychological Benefits

A systematic review and meta-analysis of 36 studies with 3,554 participants found that forest bathing significantly reduced depression and anxiety. Psychological outcomes were consistently stronger than physiological ones. The review concluded that forest therapy is a promising intervention for mental health, though more high-quality randomized controlled trials are needed.

Siah, C. J. R., Goh, Y. S., Lee, J., Poon, S. N., Ow Yong, J. Q. Y., & Tam, W.-S. W. (2023). The effects of forest bathing on psychological well-being: A systematic review and meta-analysis. International Journal of Mental Health Nursing, 32(4), 1038–1054. https://doi.org/10.1111/inm.13131

Emotional Well-being and Stress Reduction

A systematic review of randomized controlled trials found consistent reductions in stress, negative emotions, and anxiety after participation in forest therapy programs. Several studies also noted improvements in mood and life satisfaction. While emotional benefits are strongly supported, study designs varied in length and intensity of interventions.

Kotera, Y., Richardson, M., & Sheffield, D. (2020). Effects of Shinrin-yoku (forest bathing) and nature therapy on mental health: A systematic review and meta-analysis. International Journal of Mental Health and Addiction, 20(1), 337–361. https://doi.org/10.1007/s11469-020-00363-4

Physical Health and Cardiovascular Outcomes

A systematic review of Shinrin-yoku (forest bathing) interventions showed reductions in systolic and diastolic blood pressure and heart rate across multiple controlled studies. Evidence indicated potential cardiovascular benefits, particularly for pre-hypertensive and hypertensive individuals, though methodological differences limited comparability.

Ideno, Y., Hayashi, K., Abe, Y., Ueda, K., Iso, H., Noda, M., & Lee, J. S. (2017). Blood pressure-lowering effect of Shinrin-yoku (forest bathing): A systematic review and meta-analysis. BMC Complementary and Alternative Medicine, 17, 409. https://doi.org/10.1186/s12906-017-1912-z

Immune Function and Forest Exposure

Systematic reviews synthesizing experimental studies found that forest therapy increased natural killer (NK) cell activity and enhanced immune-related proteins. These changes were observed days to weeks after forest exposure, suggesting both immediate and sustained effects on immune function. However, the evidence base remains small and heterogeneous.

Chae, Y., Song, C., & Ideno, Y. (2021). The effects of forest therapy on immune function: A systematic review. International Journal of Environmental Research and Public Health, 18(16), 8440. https://doi.org/10.3390/ijerph18168440

Forest Therapy Enhances Immune Function in Cancer Patients

A study examined the effects of forest therapy, also known as "Shinrin-yoku" or forest bathing, on immune function in cancer patients. The research found that a single forest therapy session significantly increased natural killer (NK) cell activity and the number of NK cells in the participants. These effects were observed to persist for up to 30 days following the session. The study suggests that forest therapy may bolster the immune system, potentially aiding in cancer prevention and recovery.

Li, Q., Kobayashi, M., Inoue, Y., Kawada, T., & Li, Y. (2022). Effects of forest environment (Shinrin-yoku/Forest bathing) on human natural killer activity and intracellular anti-cancer proteins. International Journal of Environmental Research and Public Health, 19(4), 1770. https://doi.org/10.3390/ijerph19041770

Children and Adolescents

Studies of children and adolescents show potential benefits for reducing stress and improving social skills, but evidence remains weak compared to adult studies. One systematic review noted preliminary findings that forest-based interventions may support emotional regulation in youth and reduce severity of conditions such as atopic dermatitis, but results were inconsistent.

Stier-Jarmer, M., Throner, V., Kirschneck, M., Immich, G., Frisch, D., & Schuh, A. (2021). The psychological and physical effects of forests on human health: A systematic review of systematic reviews and meta-analyses. International Journal of Environmental Research and Public Health, 18(4), 1770. https://doi.org/10.3390/ijerph18041770

Park Prescriptions and Stress Reduction in Low‑Income Parents

A randomized trial with 78 low-income parents compared a supported park prescription program (including group nature outings, reminders, and transportation) to a basic independent prescription. Over three months, parental stress and loneliness decreased, physical activity and weekly park visits increased, and nature affinity improved. The study demonstrates that structured nature interventions can effectively reduce stress and enhance well-being in low-resource populations.

Razani, N., Morshed, S., Kohn, M. A., Wells, N. W., Thompson, D., Alqassari, M., Agodi, A., Rutherford, G. W., & others. (2018). Effect of park prescriptions with and without group visits to parks on stress reduction in low‑income parents: SHINE randomized trial. PLOS ONE. https://doi.org/10.1371/journal.pone.0192921

Nature-Based Education Improves Health-Related Quality of Life in Low-Income Youth

A 15-week nature-based education intervention was conducted with 362 youth ages 9–15 from low-income backgrounds. Post-intervention, participants demonstrated improvements across multiple health-related quality of life domains, including emotional, physical, social, and school functioning, compared to a control group. This study highlights that structured exposure to nature can enhance overall well-being in children from socioeconomically disadvantaged communities.

Sprague, N., Berrigan, D., Ekenga, C. C., & others. (2021). The impact of nature-based education on health-related quality of life among low-income youth: Results from an intervention study. Health & Place. https://pubmed.ncbi.nlm.nih.gov/33415330/

Overall Evidence Quality

A large umbrella review analyzing 11 systematic reviews (covering 131 primary studies) concluded that forest-based interventions are beneficial for cardiovascular health, immune function, and mental health. However, many reviews were rated as low or critically low in methodological quality, highlighting the need for more rigorous, long-term studies to strengthen the evidence base.

Stier-Jarmer, M., Throner, V., Kirschneck, M., Immich, G., Frisch, D., & Schuh, A. (2021). The psychological and physical effects of forests on human health: A systematic review of systematic reviews and meta-analyses. International Journal of Environmental Research and Public Health, 18(4), 1770. https://doi.org/10.3390/ijerph18041770