Yoga and Meditation Improve Mental Health, with Outdoor Settings Offering Additional Benefits Where Differences Exist: A Systematic Review

Abstract

Yoga and meditation are increasingly used to promote mental health and well-being. Exposure to nature has also demonstrated effects on mental health, leading to the development of nature-based interventions. Combining yoga or meditation with nature exposure may have cumulative or synergistic effects. This systematic review aimed to examine the effects of outdoor yoga and meditation interventions on mental health and compare the effects with equivalent indoor interventions. A systematic search was conducted. Titles and abstracts of articles, then full-text articles, were reviewed for inclusion. Study data were then extracted. Risk of bias among the included studies was assessed. Fourteen articles were included, representing 13 unique studies. Two studies compared yoga and 11 studies compared meditation in indoor versus outdoor settings. Of the 13 studies, 12 reported significant time effects on at least one mental health outcome. Six studies reported significant group-by-time effects in favor of the outdoor interventions on at least one mental health outcome, with group-by-time effects consistently favoring the outdoor interventions when found. Depression and mindfulness were the most frequently examined outcomes, measured in almost half of all studies. Overall, findings regarding the effects of nature-based yoga and meditation are limited but promising. There is strong evidence that outdoor yoga and meditation interventions improve mental health outcomes, but less clear evidence of whether they outperform equivalent indoor interventions. The greatest support was found for nature-based yoga and meditation interventions in alleviating symptoms of stress and depression and improving mindfulness. More research on nature-based yoga and meditation is needed.