One of the ways in which STH can improve mental health is through stress relief – this can show in physiological changes and cognitive restoration.
- A systematic review and meta-analysis of the literature on the effectiveness of horticultural therapy in countering stress found overall positive effects on psychological indicators and an insignificant effect on physiological indicators. 31 studies were included, with a range of 8 – 113 participants in a range of settings [Lu S., Liu J., Xu M., Xu F., Horticultural therapy for stress reduction: A systematic review and meta-analysis. Frontiers in Psychology 26 July 2023. available at https://www.frontiersin.org/journals/psychology/articles/10.3389/fpsyg.2023.1086121/full]
- A systematic review of 43 papers looking at the quantitative measures of the impact of nature viewing, outdoor walks, outdoor exercise, and gardening, found reductions in the experience of stress, heart rate and blood pressure. [Kondo, M. C., Jacoby, S. F., & South, E. C. (2018). Does spending time outdoors reduce stress? A review of real-time stress response to outdoor environments. Health & place, 51, 136-150.]
- A study of 59 older adults split them into two groups: 29 to a horticultural therapy (HT) programme and 30 on a waiting list. They attended weekly sessions for 3 months, and then monthly sessions for the next 3 months. Bio-marker IL-6 (associated with inflammation) was significantly reduced in the HT group, and there was a significant increase in social connectedness. [Ng K.S.T. and others, (2018). Effects of horticultural therapy on Asian older adults: a randomized controlled trial. International Journal of Environmental Research and Public Health.15(8):1705. https://doi.org/10.3390/ijerph15081705]