The Science of Forest Bathing: What Studies Actually Measure, and Where the Evidence Falls Short

Forest bathing—the Japanese practice of shinrin-yoku, which means slowly and mindfully immersing yourself in a forest atmosphere rather than hiking for exercise—has one benefit that researchers keep finding again and again: stress reduction. Studies have measured real changes in stress hormones, heart rate, blood pressure, and even brain activity after time spent among trees, alongside self-reported improvements in anxiety and low mood. But the evidence has honest limits: many studies are small, brief, and conducted mostly on healthy people, so the long-term picture remains uncertain. Here is what the research does show, how those effects are measured, and how to try the practice yourself.

Physiological Benefits: Impact on the Body

The most consistently demonstrated effect of forest bathing is a drop in the body's stress chemistry. Japanese research since 2004 has grown into an interdisciplinary field its practitioners call Forest Medicine, and systematic reviews summarized by the Association of Accredited Naturopathic Medical Colleges report that forest bathing reduces stress hormones including cortisol, epinephrine, and norepinephrine, while also improving immune function and cardiovascular and metabolic health.

Cortisol is the marker researchers track most often, typically through simple salivary tests. A 2024 pre-post study of 29 stressed volunteers found that two days of forest immersion significantly lowered salivary cortisol, a finding echoed in a 2019 meta-analysis showing forest groups with significantly lower cortisol than urban-walking groups. The effects can appear quickly: even a first session produces a measurable change, which makes forest bathing a practical, low-cost tool for acute stress relief.

Cardiovascular markers tell a similar story. Kaiser Permanente's overview of the practice notes that shinrin-yoku can lower blood pressure and heart rate, helping shift you into a calmer, more relaxed state. A 2025 study comparing a 30-minute forest walk with a city walk found that heart rate variability—a physiological sign of relaxation—was significantly higher after the forest walk, indicating the body had moved into a parasympathetic "rest and digest" mode.

There is also early brain-imaging evidence. One study found that a two-hour forest session reduced activity in the prefrontal cortex during a stress test, while urban exposure did not. Interestingly, the same 2025 comparison study found cortisol dropped more after the urban walk (2.1 ng/mL) than the forest walk (a non-significant 0.5 ng/mL), suggesting the physical act of walking itself—not only the setting—can lower cortisol, and that effects depend on the specific environment and duration.

Psychological Benefits: Enhancing Mental Well-being

The mental effects of forest bathing are measured mainly through self-report scales for mood, anxiety, and depression, and the results point in a encouraging direction. A 2023 meta-analysis published in The Journal of Mental Health Nursing, covering nine studies on anxiety and twelve on depression, found participants reported improvements in symptoms after forest bathing experiences. Even a single session has been shown to ease symptoms linked to anxiety and low mood, according to MedShadow's review of the science.

Forest bathing also appears to pair naturally with mindfulness. A 2025 narrative review by Hongxia Chen, Zhongji Meng, and Jie Luo in Frontiers in Public Health notes a significant positive correlation between exposure to nature, mindfulness practices, and improved psychological well-being, with both showing potential efficacy in alleviating mental health struggles associated with the COVID-19 pandemic and other uncertain events.

Everyday well-being may benefit at lower doses, too. Kaiser Permanente points to research finding that spending just 20 minutes a day outdoors can reduce stress and increase happiness, and that time in an urban park improves a person's sense of well-being. In one recent study, forest bathers also reported improved sleep quality and feeling refreshed—though sleep findings like this rest on participants' own reports rather than objective measurement.

Measured Benefits of Forest Bathing: Body and Mind

The table below separates the effects researchers have documented into bodily and mental domains, and shows how each is typically measured in studies. Use it to see at a glance what scientists actually test when they study shinrin-yoku—and what the markers can and cannot tell you.

One caveat belongs right beside this table: the cortisol comparison is not settled. While meta-analytic evidence favors forest over urban settings, at least one 2025 study found the urban walk produced the larger cortisol drop, so treat any single marker as one piece of a larger stress-relief profile rather than proof on its own.

Understanding Research Limitations and Future Directions

A balanced read of the science requires acknowledging where it is thin. Systematic reviews note that while forest bathing shows promising short-term benefits—reduced stress and improved mood—its long-term impact is less certain, and researchers highlight the need for more rigorous, large-scale studies to understand the practice's potential over time. The optimal "dosage" of forest bathing also remains unclear.

Sample size and study design are recurring weaknesses. Preliminary studies in this space have often involved small numbers of participants and relied on subjective measures, which means more research is needed before drawing broad conclusions. MedShadow's reporting adds a key caveat from Dr. Muir: although the studies showing benefits are "overwhelmingly positive," they mostly focus on relatively healthy people, so the findings may not extend to those managing chronic conditions.

There is also no clear picture of how forest bathing stacks up against other treatments, because the comparative research simply has not been done at scale. Experts agree that larger, more robust studies are needed to fully understand the true impact of the practice. None of this means the benefits are illusory—it means the strongest honest claim is that short-term stress reduction is the most reliable finding, and everything beyond that awaits better evidence.

Embracing Nature for Well-being: A Mindful Practice

You can integrate mindful forest bathing into your routine as a natural approach to stress reduction and mood improvement, recognizing its scientifically supported benefits within current research limitations. The practice is deliberately simple: find a wooded area or park, leave the pace of exercise behind, and walk slowly while engaging your senses—what you see, hear, and smell around you. Kaiser Permanente suggests even 20 minutes outdoors daily can make a difference, so a modest start is fine. This is a wellness practice, not a medical treatment, and it should not replace care for any health condition.

A useful way to gauge whether it is working for you is a noticeable reduction in personal stress levels or an improvement in mood after a mindful forest bathing session. That self-check mirrors exactly what researchers measure in their studies, and it gives you a concrete, personal indicator of the same effects the science has begun to document.

Sources

• Forest bathing: What it is, its benefits, and how to try it — Kaiser Permanente
• AANMC
• Can forest bathing significantly reduce stress hormones? — WisPaper
• Frontiers | Combined Effect of Walking and Forest Environment on Salivary Cortisol Concentration
• Why Forest Therapy Can Be Good for Your Body and Mind — Cleveland Clinic
• The Medical Science Behind Forest Bathing — MedShadow Foundation
• Frontiers | Is forest bathing a panacea for mental health problems? A narrative review