Picture yourself sitting on a stone in the forest, closing your eyes, and simply breathing for a few minutes. You hear no cars. You feel the dampness of moss, the scent of resin, the coolness of air filtered through leaves. Your heart rate slows. Your shoulders drop. Something that can’t be captured in a single word lets go.
For a long time this was dismissed as pure poetry – a subjective, pleasant, but unmeasurable feeling. Today we know it’s physiology. What you feel in the forest shows up in cortisol levels in the blood, in immune system activity, in brainwaves, and in blood pressure. The forest acts on the human body like medicine – except without a leaflet, without a prescription, and without side effects.
What Is Shinrin-Yoku and Where Does It Come From?
Shinrin-yoku – literally “forest bathing” or “taking in the forest atmosphere” in Japanese – is a term the Japanese Ministry of Agriculture, Forestry and Fisheries officially introduced in 1982. It wasn’t just a tourism campaign. It became a health program that Japan funded with public money, and one that quickly caught the attention of scientists worldwide.
The concept didn’t come out of nowhere. In Japanese culture, forests have always held a special place – as a spiritual, therapeutic, and communal space. Shinto and Buddhist traditions treat the forest as a living organism deserving of respect, not a resource to exploit. When Japanese society urbanized rapidly in the 1980s, and rates of lifestyle diseases and burnout began to climb, returning to the forest became an institutional response. Japan invested in a network of more than 60 certified forest-bathing trails and launched more than a dozen research centers studying the therapeutic effects of forests on human health.
Today, shinrin-yoku is a recognized health practice in Japan, South Korea, Germany, and many other countries. It’s an integral part of preventive medicine and rehabilitation programs. And the science behind it keeps growing richer and harder to ignore.
What Happens to Our Bodies When We Enter a Forest?
The key to understanding how the forest works lies in phytoncides – biologically active volatile compounds released by trees. Pines, cedars, firs, oaks, and most conifer species release a mix of terpenes, phenols, and other organic compounds into the air, which serve a protective function for the tree itself – repelling insects and inhibiting the growth of fungal and bacterial pathogens. For a person breathing forest air, the effect is entirely different.
Japanese researcher Qing Li of Nippon Medical School in Tokyo conducted a series of pioneering studies measuring the physiological effects of time spent in forests. The results were unambiguous: after a two-day stay in the forest, the activity of NK cells (natural killer cells) – white blood cells that play a key role in fighting viral infections and cancer cells – increased in participants by an average of 50 percent. What’s more, the effect lasted for over a week after returning to the city. A single short weekend trip to the forest delivered a week’s worth of immune boost.
At the same time, researchers measured cortisol levels – the stress hormone – in blood and saliva. Time spent in the forest lowered it significantly compared to spending the same amount of time in an urban environment. Blood pressure dropped, heart rate slowed, and activity of the sympathetic nervous system, responsible for the “fight or flight” response, decreased. The body shifted from a state of combat readiness into a state of recovery.
Why the Trees Themselves Matter
Not every green environment works the same way. Comparative studies conducted in Japan and Germany showed that a walk in a city park – even a well-kept one, full of greenery – doesn’t trigger physiological effects as strong as a walk through a genuine, multi-species forest. The key appears to be phytoncide concentration, which is many times higher in dense forest than in scattered urban tree plantings. Species diversity and tree age also matter – an old forest with trees of different species, sizes, and life stages produces a richer, more varied air chemistry than a monoculture of young pines.
This matters both for therapists and for people involved in restoring green spaces. A forest isn’t synonymous with “trees planted in one place.” A forest is an ecosystem – complex, multi-species, connected by a web of biological relationships, which we explore further in our article on mycorrhizae and underground forest networks.
The Research – What Do the Numbers Say?
Over the past three decades, hundreds of scientific papers have been published on how forest environments affect human health. Meta-analyses covering tens of thousands of participants now allow conclusions to be drawn with strong statistical confidence. Here are some of the most striking figures:
- Regular contact with forests lowers the risk of depression by 30-40% compared to people living without access to forested areas.
- A 15-minute walk in the forest lowers cortisol levels by an average of 12.4% and systolic blood pressure by 1.9 mmHg – effects comparable to some anti-stress medications.
- Children with ADHD show a significant improvement in concentration after just 20 minutes of play in a forest setting, comparable to the effect of a low dose of methylphenidate.
- Hospitalized patients whose windows looked out onto trees were discharged an average of one day earlier and took fewer painkillers than patients with a view of a wall – the famous 1984 study by Roger Ulrich that launched the entire field of biophilic design.
- In South Korea, forest therapy programs for veterans and people with PTSD showed a reduction in post-traumatic stress symptoms of more than 20% after just four sessions.
These numbers are all the more striking given that no one is taking any medication. No one is performing special exercises. All it takes is being in the forest – breathing, listening, looking. What sounds like a cliché turns out to be one of the most effective and safest health interventions medicine knows.
Forests and Mental Health – Attention Restoration Theory
The biological explanation involving phytoncides is only one layer. In parallel, researchers in environmental psychology have tried to understand what happens to our minds when we enter a forest. Two complementary theories provide the answer.
Attention Restoration Theory, formulated by Rachel and Stephen Kaplan in the 1980s, holds that natural environments have a unique ability to restore what’s called directed attention – the capacity we draw on heavily during work that demands concentration, decision-making, and filtering information. Directed attention depletes like a battery; using it constantly without rest leads to cognitive errors, irritability, and burnout. The forest – with its “soft fascination,” which draws the eye without requiring effort (the rustle of leaves, the play of light, the movement of birds) – lets directed attention rest and recover.
Stress Recovery Theory, developed by Roger Ulrich, focuses instead on the emotional and physiological response. Natural environments trigger an automatic, evolutionarily encoded relaxation response, because for hundreds of thousands of years they were a safe, resource-rich environment for humans. The city – with its noise, sensory overload, and unpredictability – switches on mechanisms of vigilance and stress. The forest switches them off.
When the Forest Replaces Therapy
A growing number of psychiatrists and psychotherapists are incorporating forest therapy as a complement to treating depression, anxiety disorders, and burnout. In Scandinavia and Japan, specialized forest therapy centers operate where treatment programs include regular forest sessions as a first-line element, not merely a recreational add-on. Clinical results are promising: forest therapy proves especially effective when combined with traditional therapeutic methods, shortening treatment time and improving the durability of results.
Not All Greenery Is Equal – Why Biodiversity Matters
Understanding the mechanisms of shinrin-yoku carries another important message: not all greenery is equal. Not every “forest” – in the sense of an area covered with trees – offers the same therapeutic potential.
Research conducted in Germany and Japan, among other places, clearly shows that multi-species forests with a rich understory, dead wood, and a varied age structure of trees work more powerfully than forest monocultures. Pine monocultures, which cover a significant portion of Poland’s managed forests, produce a poorer range of phytoncides, have reduced biodiversity, and carry a higher risk of mass disease outbreaks that could wipe the forest out within a few years. A certified, multi-species forest with a preserved ecosystem structure – for instance, a naturally structured forest or one restored using close-to-nature methods – offers far more, both to the ecosystem and to the person walking through it.
This is an argument for treating tree planting not as filling a quota of greenery, but as building genuine ecosystems. No one needs convincing of how important proper environmental education is for understanding these distinctions – but it’s worth saying out loud.
How to Practice Forest Bathing – A Practical Guide
Shinrin-yoku requires no special equipment, no backpack, no physical conditioning. It requires one thing: presence. That’s precisely what sets it apart from trekking or Nordic walking – it isn’t about distance or pace, but about consciously immersing yourself in the forest environment.
The basic rules of practice:
- Leave your phone in your pocket or in the car. Digital stimuli activate exactly the brain regions the forest has a chance to quiet. Two uninterrupted hours in the forest without a screen produce a far stronger effect than four hours with a phone.
- Go slowly. The ideal pace isn’t a brisker walk – it’s slower than usual. Research suggests the best effects come with a distance of 2-4 km over 2 hours. What matters is time spent exposed to the environment, not distance covered.
- Engage all your senses. Touch the bark of a tree. Smell the forest floor after rain. Listen to the sounds of the forest separately – first the distant ones, then the nearby ones. Studies confirm that multisensory engagement strengthens the therapeutic effects.
- Stop and sit down. Staying still in the forest – sitting under a tree, lying on moss – is at least as beneficial as walking. Japanese comparative studies found that 40 minutes of sitting in the forest produces a cortisol effect similar to 40 minutes of forest walking.
- Go regularly, not occasionally. A one-off visit produces short-lived effects. Going to the forest regularly, once every week or two, builds lasting physiological changes, including improved immune parameters and reduced chronic stress.
Where to Find Real Forests in Poland
Poland is fortunate in this regard. Białowieża National Park, Tuchola Forest, Kampinos Forest, Roztocze, Magura National Park, the Drawsko Lake District – these are areas where the forest has retained its natural, multi-species character or comes close to that ideal. But even near large cities, there are pockets of older, diverse forest worth returning to regularly.
Why We Need More Forests – and Why Every Planted Tree Matters
Shinrin-yoku sounds like a beautiful philosophy – but it carries hard political and ecological consequences. If the forest genuinely heals, then access to forests is a matter of public health. Meanwhile, in Poland and many other European countries, forested areas are shrinking or degrading – due to deforestation, intensive sanitary logging, soil acidification, and climate change, all of which weaken trees and favor pest outbreaks.
Data from Poland’s Central Statistical Office shows that more than 60% of Poles live in cities or their immediate surroundings, where access to genuine forested areas is limited. Many people go entire weeks without any contact with a natural environment at all. The health consequences of this state of affairs – higher rates of depression, anxiety disorders, cardiovascular disease – are measurable and documented in successive epidemiological studies.
The answer is planting trees – but not just any trees, anywhere. An urban forest planted with biodiversity in mind, with varied species, a layered vegetation structure, and room for other organisms, gives city dwellers something no park with regularly mowed grass and a row of lindens ever could. Every tree planted with the ecosystem in mind – not merely to fill a green quota – brings us closer to the moment when forests will be accessible to those who need them most.
That’s why initiatives such as tree planting that supports the health of urban environments matter far beyond ecology alone. They matter medically. Every planted tree is a fragment of a future forest that someone, someday, will need – to rest, to heal from burnout, to feel that the world is bigger than a screen.
The Forest Is for Everyone – But Only If We Look After It
Shinrin-yoku is democratic in theory – a forest requires no admission ticket. But it is deeply unequal in practice, because access to a real, healthy forest depends on where you live, how physically able you are, and whether a forest even exists nearby. Older people, people with disabilities, children from poorer city neighborhoods – these are the groups that benefit least from access to nature, even though they could benefit from it the most.
Building accessible therapeutic forest spaces, creating urban forests designed with health and inclusion in mind, and educating the public about what a real forest is and why it’s irreplaceable – these are tasks that require cooperation among environmental organizations, local governments, health institutions, and citizens. These aren’t utopian goals. Japan did this forty years ago. South Korea is building a network of public forest therapy centers today, accessible to every insured citizen. Germany publicly funds forest programs for children and young people.
Poland has the forests. It has the knowledge. It has growing environmental awareness. What it lacks are systemic decisions that start from a simple recognition: a forest is not a resource. A forest is health infrastructure. And like any infrastructure, it must be built, protected, and maintained with an eye toward those who will rely on it – today and fifty years from now.
Every tree counts. Every forest is needed. And anyone who has ever come back from a walk in the forest calmer, healthier, and more themselves knows this better than any statistic.
