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Forest bathing (shinrin-yoku)

Structured, slow sensory exposure in real forest settings—often called shinrin-yoku—is associated in field trials and meta-analyses with short-term lower blood pressure, improved mood scales, higher HF-HRV, and lower salivary cortisol versus built-environment controls; certainty is often low, so treat as wellness adjunct to clinical care.

What this protocol is

Shinrin-yoku (森林浴, “forest bathing”) here means guided or self-paced quiet walking and sensory attention in living forests, contrasted with urban or indoor control conditions in research—not indoor aromatherapy alone.

Typical practice (evidence-informed, not prescriptive)

  • Duration: studies commonly use roughly 15–120 minutes per session, sometimes repeated over days.
  • Pace: slow walking or seated rest; emphasis on sight, sound, and smell of the forest.
  • Safety: stay on marked trails; consider allergies, footing, heat, and local wildlife.

Physiological themes in the literature

  • Serotonin / endocrine pilots (small field trials): Park et al. 2020 (Int J Environ Res Public Health; PMID 32560522; park-2020-forest-therapy-middle-aged-women-serotonin-ijerph) compared 3-day forest vs urban programmes in 53 middle-aged women—paired analyses reported statistically significant blood serotonin increases after forest segments (vitamin D shifts not significant). Non-randomised sequence design: hypothesis tier next to cortisol meta-analyses below.
  • Autonomic / HRV: narrative reviews of field experiments often report higher high-frequency HRV in forest versus urban settings.
  • Blood pressure: a 20-trial meta-analysis (n≈732) favored lower SBP/DBP in forest versus non-forest environments.
  • Stress biomarkers: dedicated meta-analyses report lower salivary cortisol after forest exposure in pooled eligible trials.
  • Mood: short-term POMS subscale improvements appear in some meta-analyses, but GRADE is frequently very low—heterogeneity and bias risk are real.

How to read the evidence

Use the linked PubMed systematic reviews first. Wikipedia and magazine articles are included only as orientation and cultural context, not as outcome evidence.

Broader greenspace umbrella (not shinrin-only)

Twohig-Bennett & Jones 2018 (Environ Res; PMID 29982151; twohig-bennett-2018-greenspace-health-meta) synthesises parks, woodland, gardens, and residential greenness across 143 studies—pooled mortality, BP, HR, cortisol, and HF-HRV signals complement the forest-vs-urban trial rows above while carrying ecologic confounding and high heterogeneity caveats.

Related registry entries

  • Daily sunlight — daylight timing and vitamin D context when you combine sun with treed trails.
  • Mindfulness meditation — overlapping attentional skills; forest programs sometimes blend both.
  • Walking for glucose control — if you use post-meal walks in green space for metabolic goals.

Tertiary map

Wikipedia: Green exercise (wikipedia-green-exercise-overview) orients physical activity in natural settings (parks, trails, coastlines)—often higher exertion than slow sensory shinrin-yoku field trials; pooled BP, cortisol, HF-HRV, and mood estimates remain PubMed-first on this page.

Evidence