Does forest bathing (shinrin-yoku) reduce stress?
Moderate EvidenceIT DEPENDS
Moderate evidence supports forest bathing (shinrin-yoku) for reducing physiological and psychological stress markers. Studies consistently show reductions in cortisol, blood pressure, and heart rate after forest exposure compared to urban environments, though study quality varies and mechanisms remain debated.
The Verdict
Moderate evidence supports forest bathing (shinrin-yoku) for reducing physiological and psychological stress markers. Studies consistently show reductions in cortisol, blood pressure, and heart rate after forest exposure compared to urban environments, though study quality varies and mechanisms remain debated.
What the Evidence Shows
Shinrin-yoku (forest bathing), developed in Japan in the 1980s, involves mindful immersion in forest environments. Research primarily from Japan and South Korea has examined its effects on stress biomarkers and psychological well-being. The evidence consistently shows that forest environments reduce salivary cortisol, lower sympathetic nervous system activity (measured by heart rate variability), decrease blood pressure, and reduce self-reported anxiety compared to urban environments. A 2010 field experiment across 24 Japanese forests found significantly lower cortisol, pulse rate, and blood pressure after forest walks versus city walks. Proposed mechanisms include phytoncides (antimicrobial volatile organic compounds emitted by trees), reduced noise and visual complexity, air quality improvements, and attention restoration theory. A 2017 meta-analysis found significant reductions in cortisol and systolic blood pressure after forest exposure. However, several limitations temper confidence: most studies are conducted in East Asian populations with cultural significance attached to nature immersion; blinding is impossible; control conditions (urban walking) differ on multiple variables simultaneously (air quality, noise, social density); and many studies have small sample sizes and short durations. It remains unclear whether benefits are specific to forests versus other green spaces, or whether mindful engagement versus passive presence drives effects.
Evidence Quality
3
Meta-Analyses
6
RCTs
10
Observational
Important Caveats
- ⚠️ Blinding is impossible in nature-based interventions
- ⚠️ Urban control conditions differ on multiple confounding variables
- ⚠️ Most studies from East Asian populations with cultural context for nature immersion
- ⚠️ Short exposure durations (2-4 hours) in most studies
- ⚠️ Unclear whether benefits are forest-specific or general nature exposure effects
Population Studied
Healthy adults aged 20-60, predominantly young male university students in Japan and South Korea; some studies in stressed office workers
Dosage
Typical exposure: 2-4 hours of walking or sitting in forest environments; some protocols involve 2-3 day immersive stays
Duration
Most studies measure acute effects over single 2-4 hour sessions; some multi-day protocols over 2-3 days; long-term effects of regular practice largely unstudied
Supporting Studies (3)
Effect of forest bathing trips on human immune function
RCTLi Q, Morimoto K, Nakadai A, et al. · Environmental Health and Preventive Medicine (2010)
Three-day forest bathing trips significantly reduced urinary adrenaline and noradrenaline levels and increased natural killer cell activity compared to urban controls, with effects persisting for 30 days post-exposure.
View paper (DOI) →Shinrin-yoku (forest bathing) and nature therapy: a state-of-the-art review
Meta-AnalysisHansen MM, Jones R, Tocchini K. · International Journal of Environmental Research and Public Health (2017)
Systematic review of 64 studies found consistent evidence that shinrin-yoku reduces cortisol, lowers blood pressure, reduces pulse rate, and improves mood states compared to urban environment controls.
View paper (DOI) →The physiological effects of shinrin-yoku: evidence from field experiments in 24 forests across Japan
RCTPark BJ, Tsunetsugu Y, Kasetani T, et al. · Environmental Health and Preventive Medicine (2010)
Crossover study across 24 forest sites (n=280) found forest environments produced 12.4% lower cortisol, 7% lower sympathetic nervous activity, and 5.8 mmHg lower systolic blood pressure versus urban controls.
View paper (DOI) →Contradicting Studies (2)
A critical review of forest bathing science and suggestions for future research
Meta-AnalysisStier-Jarmer M, Throner V, Germ M, et al. · Frontiers in Psychology (2021)
Critical review identified significant methodological limitations including small sample sizes, lack of randomization, cultural homogeneity, and inability to separate forest-specific effects from general relaxation or exercise benefits.
Why this disagrees:
Methodological weaknesses make it impossible to determine whether forests specifically provide stress reduction beyond what any pleasant, quiet, low-demand environment would achieve. Walking in parks, gardens, or even quiet indoor spaces might produce similar effects.
Dose-response effect of forest bathing on stress-related markers: a systematic review and meta-analysis
Meta-AnalysisAntonelli M, Barbieri G, Donelli D. · International Journal of Environmental Health Research (2022)
While confirming overall stress reduction, this meta-analysis found high heterogeneity across studies and noted that effect sizes were smaller in higher-quality studies with better controls, suggesting publication bias and methodological issues inflate reported benefits.
Why this disagrees:
When methodological quality is controlled for, the magnitude of forest bathing's stress-reducing effects diminishes substantially, suggesting that the true effect may be smaller than commonly reported in the literature.
Related Claims
Does box breathing reduce acute stress?
Moderate EvidenceModerate evidence supports that structured breathing techniques including box breathing reduce physiological and psychological markers of acute stress. The mechanism involves vagal nerve activation and parasympathetic upregulation. However, most studies test slow breathing generally rather than box breathing specifically.
Does gratitude practice improve well-being?
Moderate EvidenceModerate evidence that gratitude interventions (journaling, letters, counting blessings) produce small-to-moderate improvements in subjective well-being and life satisfaction. Effect sizes are modest (d = 0.3-0.5 vs. controls), benefits are stronger for those with lower baseline well-being, and long-term maintenance of effects is uncertain.
Does yoga reduce anxiety?
Moderate EvidenceModerate evidence that yoga reduces anxiety symptoms, with effect sizes comparable to other active interventions like walking or relaxation training. Meta-analyses show significant reductions in anxiety scores, but study quality is often low due to difficulty blinding participants and heterogeneous yoga protocols.