Forest therapy may reduce blood pressure and stress in people living in urban settings 

Qiu Q, Yang L, He  Mei, et al. The effects of forest therapy on the blood pressure and salivary cortisol levels of urban residents: A meta-analysis Int J Environ Res Public Health. 2022;20:458.

Review question

Does forest therapy reduce blood pressure and mental stress in people living in urban settings?

Background

Urban living can expose people to triggers like pollution, noise, and light, which can impact both mental and physical health. Compared to rural environments, which tend to provide more access to green space and nature, some studies have linked urban environments to higher blood pressure and levels of the stress hormone cortisol. Forest therapy involves intentionally and fully immersing oneself and one’s senses in nature (e.g., a forest setting). Previous meta-analyses on forest therapy’s effect on blood pressure, mental health, and cortisol levels have been mixed, requiring further research.     

How the review was done

This is a meta-analysis of 29 studies, most of which were randomized controlled trials. The studies were published between 2007 and 2021.

Key features of the studies were:

• Participants were adults (19 years old to 60 and over) living in urban settings.  
• Participants engaged in forest therapy, including one or more of the following: seated viewing and forest walking.
• Time spent engaging in forest therapy ranged from a single session (lasting 11 minutes to 2 hours) to multi-session programs (lasting up to 5 weeks).  
• Researchers measured changes in systolic blood pressure, diastolic blood pressure, and salivary cortisol concentration (aka a marker for stress).
• Results were compared with people in control groups engaging in seated viewing, walking or multi-session programs within urban settings.

What the researchers found

The review found that compared to the urban control group, forest therapy may lower systolic blood pressure, diastolic blood pressure, and salivary cortisol concentration (indicating stress reduction). This strategy was especially effective for those with higher blood pressure prior to starting forest therapy. Additionally, it appears that greater durations of forest therapy, specifically those lasting 20 minutes or more, may be particularly beneficial for systolic blood pressure and cortisol levels. These findings should be interpreted cautiously, as there was quite a bit of variation between the studies included in the review. Further research is needed to gain a better understanding of the link between forest therapy and stress reduction, how forest therapy impacts participants of different ages and baseline levels of blood pressure, the effects of self-guided vs. professionally guided forest therapy, and the influence of different forest settings.   

Conclusion

In adults living within urban settings, forest therapy may have the potential to lower blood pressure and relieve stress, especially through longer term programs.