Benefits of nature for human health are well documented, including mental health and wellbeing. Factors accounting for these benefits, however, are not clearly understood. This systematic review of the literature aimed “to identify any mechanisms of psychological change following exposure to nature within an adolescent population.†Identifying such mechanisms would be invaluable in designing nature-related strategies to promote the mental health of adolescents.
Twenty-seven studies were included in this review. All of the studies involved participants between 10 and 24 years of age, were published in English in peer-reviewed journals between 1996 and 2021, used experimental or quasi-experimental research methods, and assessed mental health and/or psychological outcomes of nature exposure. Studies focusing on outdoor therapy programs were not included, as the intent was to distinguish the impact of nature exposure from the impact of nature-related therapeutic interventions on mental health. Each study was assessed for quality of the research methods used and manually searched for mediation analyses, which is a statistical strategy exploring why or how two factors are related. In this case, the idea was to identify mechanisms explaining a link between nature exposure and mental health outcomes.
Studies in this review were carried out across three continents: Asia, Australasia and Europe. Twenty studies used an experimental design, seven a quasi-experimental design. Sample sizes ranged from 13 to 396. Over half of the studies (59%) had under 70 participants. One study included only females; eleven studies included only males. The other fifteen included both males and females. The type of nature exposure and contact with nature varied greatly. Sixty significant outcomes of psychological change following exposure to nature were identified. These outcomes were assigned to one of ten categories: Mood and Affect, Mental Health, Wellbeing, Perceived Restoration, Stress, Energy, Cognitive Functioning, Resilience, Self-concept and Pro-social Behaviour. Findings within each of these categories were significant, except in the areas of Self-concept and Pro-social Behavior. Only one study included a formal mediation analysis. This analysis showed that a sense of belonging directly contributed to increases in resilience.
The findings of this review indicate that exposure to nature has a positive impact on outcomes of psychological change in adolescents. “Firm conclusions on key mechanisms, however, cannot be made, given that the studies in the current review are methodologically limited and there is a paucity of mediation analyses.†These findings highlight the need for future research focusing on the potential mediators of nature exposure on wellbeing in adolescents. Ideally, this research would include robustly controlled, experimental studies with longitudinal designs.
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