What the research says

The short version

Shinrin-yoku was named in Japan in 1982, and Japanese researchers began studying it in the 1990s and 2000s. Since then, studies in Japan, South Korea, China, Europe and North America have compared people who spend time in woodland with people who spend similar time in a city. The usual finding is that people who spend time in woodland show lower stress and better mood, and some studies report small changes in blood pressure and heart rate.

That is a useful and consistent result. It does not show that forest bathing treats any illness. Most studies are small, short and hard to blind, and reviews of the field regularly say that more rigorous work is needed.

Nothing on this page is medical advice. If you have a health condition, talk to a doctor or nurse before changing how you manage it.

Main findings

Stress hormones and heart rate

A widely cited set of field experiments in 24 Japanese forests, led by Yoshifumi Miyazaki, Bum-Jin Park and colleagues and published around 2010, found lower cortisol, pulse rate and blood pressure after forest walks compared with city walks. Later reviews of such studies have found a similar direction of effect for cortisol and blood pressure, with a lot of variation between studies.

Mood and anxiety

Studies using questionnaires commonly report less tension, anger and fatigue, and more vigour, after a forest visit. Because these rely on how people say they feel, and participants know where they have been, expectation may account for part of the effect.

Immune markers

Qing Li of Nippon Medical School and colleagues reported higher activity of natural killer cells, a type of immune cell, in a small group of men after a three-day trip to forests. The finding is often quoted. It has not been firmly established, and it does not show that forest bathing protects against disease.

Time in nature and wellbeing

A 2019 study of about 20,000 people in England, led by Mathew White, found that those who spent at least two hours a week in nature reported better health and wellbeing than those who did not. It was observational, so it cannot show cause, but the result was similar across many groups of people, and it matches the Garden's suggestion of regular short visits.

Hospital views of trees

In 1984 Roger Ulrich reported that surgical patients with a window view of trees recovered a little faster and needed fewer strong painkillers than those facing a wall. It was a small study of one hospital, and it is still cited as an early sign that greenery may help.

Check the details against the original papers if you plan to rely on them. The studies named here are examples, not a complete list, and figures are deliberately left out.

Why it might work

Several explanations are proposed, and they may all play a part:

• Stress reduction. Ulrich's theory is that natural scenes calm the body's stress response, perhaps because we evolved in natural settings.
• Attention restoration. Rachel and Stephen Kaplan proposed that nature gently holds our attention without effort, which lets the tired, directed attention we use at work recover.
• The air and the plants. Trees release aromatic compounds called phytoncides, and some Japanese studies suggest they may affect the body. This idea is the least well supported, and the amounts in woodland air are small.
• Everything else that comes with it. Walking, fresh air, quiet, daylight, time away from screens and, often, company all help mood by themselves. It is hard to separate these from the trees.

Limits of the evidence

• Small studies. Many have dozens of participants, often young, healthy men in Japan, so the results may not apply to everyone.
• Short follow-up. Most measure changes within hours or days. Few track whether the effect lasts months.
• No true blinding. People know whether they are in a forest, and may report what they expect to feel.
• Hard-to-isolate causes. A forest walk differs from a city walk in many ways at once.
• Publication bias. Studies with positive results are more likely to be published.
• Mixed quality in reviews. Systematic reviews generally conclude that results are promising, while calling for larger and better-designed trials.

How to use this

You do not need strong evidence to justify a walk in the woods. The risks are low, the cost is small and many people enjoy it. Treat it as a pleasant way to lower everyday stress, not as a treatment. A sensible reading of the research is:

• Regular, unhurried time in green places seems to help most people feel calmer.
• About two hours a week, in one visit or several, is the figure from the largest study.
• Woodland, parks and even small green spaces appear to help, though woodland is the best studied.
• It adds to medical care and does not replace it.

To keep your own record of how you feel before and after, use the journal.