Nature-based interventions show a large effect on psychological dimensions of well-being, though study limitations temper confidence in this estimate

A second-order meta-analysis pooling 30 systematic reviews of nature-based interventions, covering thousands of primary studies, examined how these interventions affect positive well-being outcomes. When positive outcomes were split by dimension, the psychological dimension (covering things like mood, positive affect and subjective well-being) showed a standardised mean difference of 1.18 (95% CI, 0.66 to 1.69) compared with control conditions, a large effect on this scale.

For those shaping green space, workplace design or care settings, this suggests that nature-based interventions probably influence how people feel psychologically more strongly than physiological measures captured in the same reviews. The mechanism implied is exposure to natural settings shifting mood and affect rather than measurable bodily changes, which bears on where planners and clinicians might expect benefit to concentrate.

Most of the underlying studies compared interventions against passive control groups and used inconsistent definitions of what counts as a nature-based intervention, according to the psychologist Esmaeel Saeedy Robat and colleagues, which weakens confidence in the precise size of this pooled estimate. The analysis draws on a synthesis of reviews rather than a single controlled trial, so it can show a consistent direction of benefit; how that benefit compares across different intervention types stays unresolved.