For thousands of years, humans have purposefully immersed themselves in forests in order to revitalize their spiritual, mental, and physical health. But in 1982, Tomohide Akiyama, director of Japan’s forestry agency, put a name to this, coining the term shinrin yoku, which can be translated as forest bathing. Since then, interest in the practice has skyrocketed among both the public and scientific researchers. And last year, forest bathing may have hit a tipping point, with four books published around the world on this natural therapeutic approach. Forest bathing seems poised to go global, as interest expands beyond Japan into South Korea, the rest of Asia, and throughout the West.

In Shinrin Yoku, The Japanese Art of Forest Bathing, Yoshifumi Miyazaki — who is a professor at the Chiba University center for environment, health, and field sciences; coiner of the term “forest therapy;” and one of the first to conduct scientific research on the health benefits of forest immersion — we have the original Japanese take on the practice.

In Japan, forest bathing and the more-regimented, often multi-day practice of forest therapy are mainstream. Companies regularly send their employees to forests to restore themselves. And Japanese go on therapeutic vacations to some of the most well-known sites of natural beauty. Today, there are some 60 official forest therapy trails, designated for the practice of shinrin yoku by the Forest Therapy Society. And there are a growing number of doctors who are certified to practice forest medicine.

Over the course of human evolution, we have spent 99.99 percent of our development in natural environments. It’s only very recently that we have, as a species, moved into dense urban areas. According to Miyazaki, this has resulted in major health issues. “We are over-stimulated and stressed by today’s man-made world, and that makes our bodies more susceptible to disease.” For him, “it’s not surprising that attention is turning to shinrin yoku as an example of a natural and low-cost way to alleviate this problem.”

In 1990, Miyazaki conducted some of the first experiments to examine the physiological effects of forest bathing on the Japanese island of Yakashima. The study had limited value because then only saliva samples measuring cortisol levels were used. Since 2000, though, the science “moved on,” yielding new ways to measure brain activity and autonomous nervous activity, “both good indicators of the level of stress in the human body.” Over the past 10-15 years, data on the benefits of forest bathing has accumulated.

Miyazaki does an excellent job of clearly communicating the dangers of stress and how forest therapy helps reduce its impacts.

Our over-stimulated urban lifestyles leads to chronic stress, which is exacerbated by “technostress,” the unique stress caused by our fixation on smart phones, twitter feeds, and Netflix accounts.

According to Miyazaki, stress causes illness such as the common cold; back, neck, and shoulder pain; slower healing; weight gain and loss, sleep dysfunction; depression; dysautonomia (autonomic nervous disorder); irritable bowel syndrome; ulcers and stomach problems; heart diseases; and increased cancer risks.

Forest therapy increases physiological relaxation, boosting our immune system and undoing the damaging effects of stress.

The benefits of forest therapy measured by Mizayaki and others include:

• “Improvement of weakened immunity, with an increase in the count of killer (NK) cells, which are known to fight tumors and infections.
• Increased relaxation of the body due to increased activity in the parasympathetic nervous system activity.
• Reduction in blood pressure after only 15 minutes of forest therapy.
• Reduced feelings of stress and a general sense of well-being.
• Reduction in blood pressure after 1 day of forest therapy, which lasts up to 5 days after therapy.”

On a deeper level, Miyazaki believes we experience these benefits when we de-synchronize with technology and the stressful pace of urban living and re-synchronize with the natural rhythms we have evolved with. Over seven million years of human evolution, “we have lived amid nature and our bodies have adapted to that nature.”

In Japan, there is a deep connection with nature. From the country-wide festivals under the beautiful, ephemeral cherry blossoms to the prayers left at the base of honored tree specimens, Japanese live with nature, as opposed to admiring it as the other. People and the natural world co-exist in a country still covered in nearly 70 percent forest. It makes sense then that the Japanese government invested greatly in research on forest therapy, some $4.3 million since 2004.

One study was conducted in 63 forests across Japan, using some 756 subjects, who were split into 6 groups in different regions. Within each group, half went to urban areas and half were sent to forested areas. Subjects were asked to walk slowly through an urban or forested environment for 15 minutes in the morning, and then just sit and look at the view for 15 minutes in the afternoon. Their autonomic nervous activity, pulse rate, blood pressure, cortisol levels were measured, and they were asked questions about how they felt. The study proved that “during forest therapy, the body experiences physiological relaxation.” And subjects in the forested areas reported an increased feeling of comfort, calm, and refreshment; an improvement in their emotional state; and reduction in anxiety.

Other studies in Japan showed that a forest therapy session reduced blood pressure among men with high blood pressure and office workers; calmed pre-frontal brain activity; and among mature women, reduced stress levels. Furthermore, if a forest isn’t accessible, spending time in a large urban park, looking at ornamental house plants, flower arrangements, or bonsai trees, or smelling wood also relaxes the body.

The book is also worthwhile as a guide to shinrin yoku on your own. Miyazaki explains how to walk mindfully in the forest, feeling the forest floor, taking in the sounds and smells, or closely studying a tree. For a therapeutic boost, he recommends meditating, stretching, or sketching in a forest.

Other notable forest bathing books published in the past year:

• Forest Bathing: How Trees Can Help You Find Health and Happiness by Dr. Qing Li
• The Joy of Forest Bathing: Reconnect with Wild Places & Rejuvenate Your Life by Melanie Choukas-Bradley and Lieke van der Vorst
• Your Guide to Forest Bathing: Experience the Healing Power of Nature by M. Amos Clifford