Does forest bathing work? The effects are real but the evidence is low-certainty

Forest bathing — shinrin-yoku, the Japanese practice of spending unhurried time among trees — is promoted as a nature-based fix for stress and low mood. The pooled trial evidence does point in that direction: forest therapy is associated with lower stress, anxiety, and blood pressure in the short term. But the studies are inconsistent, and the reviewers who assembled them rate the confidence in those effects as low to very low.

What the newest pooled analysis found

A 2026 systematic review and meta-analysis in BMC Public Health set out to quantify the effect of forest therapy on psychological stress and emotional disorders, defined as depressive and anxiety symptoms [s1]. Searching five databases through December 2024, it pooled randomized and quasi-experimental trials using validated self-report measures, ending with 25 studies and 1,876 participants [s1].

The pooled effects were moderate and all favoured forest therapy: a reduction in psychological stress (standardized mean difference −0.71, 95% CI −0.89 to −0.53), in depressive symptoms (SMD −0.68, 95% CI −0.86 to −0.50), and in anxiety symptoms (SMD −0.77, 95% CI −0.97 to −0.57) [s1]. The important caveat sits alongside them: heterogeneity was substantial across every outcome (I² greater than 74%), and under the GRADE framework the evidence quality was rated moderate for stress and low for the emotional-disorder outcomes [s1].

That combination — a clear average effect wrapped in wide variability — is the recurring signature of this field. The authors attribute the uncertainty to methodological variability across the included studies [s1]. High heterogeneity means the trials disagree substantially about the size of the benefit, which is why a single pooled number, however favourable, has to be read with caution rather than as a settled dose-response.

A second review reaches the same place

A 2026 meta-analysis in Frontiers in Psychology looked at short-term cardiovascular and mental-health responses to shinrin-yoku [s2]. From 718 records it included 11 studies, and found forest bathing associated with a reduction in heart rate (mean difference −4.00, 95% CI −6.90 to −1.09), in tension-anxiety (MD −0.79, 95% CI −1.13 to −0.46), and in depression-despondency (MD −0.68, 95% CI −1.03 to −0.34) [s2].

But heterogeneity again ran from moderate to very high (I² of 49% to 87%), and the authors rated the certainty of evidence as very low under GRADE — chiefly because of risk of bias, inconsistency, and imprecision [s2]. Their conclusion is worth quoting for its restraint: forest bathing "should be interpreted as a potential complementary practice for health promotion, and not as an individual preventive or therapeutic intervention" for cardiovascular or mental disorders [s2].

The blood-pressure signal is older and more established

The claim with the longest evidence base is the physiological one. A 2017 meta-analysis in BMC Complementary and Alternative Medicine reviewed the effect of the forest environment on blood pressure, pooling 20 trials involving 732 participants [s3]. It found that systolic blood pressure in the forest environment was significantly lower than in a non-forest environment, and that diastolic pressure was significantly lower too [s3]. That is a consistent, repeatedly measured effect — though, like the mood findings, it reflects a short-term response to being in a natural setting rather than a lasting treatment.

What it means for a reader

The pattern across all three reviews is the same. Forest bathing is repeatedly linked to short-term drops in stress, anxiety, and blood pressure, and the direction of effect is remarkably consistent [s1][s2][s3]. What is not established is durability or certainty: the trials are small and varied, self-reported outcomes dominate the mental-health findings, and two of the three most recent syntheses grade their own confidence as low or very low [s1][s2].

Read plainly, that supports a modest claim and undercuts an inflated one. Time spent walking calmly in a forest plausibly lowers stress and blood pressure for a while, and there is little downside to trying it. But it is not, on this evidence, a substitute for treatment of an anxiety disorder or depression, and the researchers assembling the data say so directly [s2]. What is missing is not a hint of effect but the harder proof: larger trials, objective outcomes, and follow-up long enough to show whether anything lasts once a person leaves the trees [s1][s2]. The honest verdict is a qualified yes — real short-term effects, weak long-term proof.