In Japan, where they’ve coined the word karoshi—death from overwork—the government is creating over one hundred forest therapy sites for people to engage in shinrin yoku, forest bathing. Williams visited Yoshifume Miyazaki, a physical anthropologist whose research found that when people take forest walks, there is a 12 percent decrease in cortisol (your body’s main stress hormone), a 7 percent decrease in sympathetic nerve activity (which governs fight-or-flight behavior), a 1.4 percent decrease in blood pressure, a 6 percent decrease in heart rate, and a better mood and lower anxiety. In a country with a high suicide rate and tsukin jigoku—commuting hell—where workers shove you into a train during rush hour, nearly 25 percent of the population now walk forest therapy trails yearly. As Miyazaki explains, “we’ve spent 99.9 percent of our time in nature, a feeling of comfort can be achieved if our rhythms are synchronized with those of the environment.”
Immunologist Qing Li, a collaborator with Miyazaki, has studied natural killer (NK) immune cells, a type of white blood cell that can send self-destruct messages to tumors and virus-infected cells. Sure enough, three days of hiking boosted these NK cells by 40 percent for an entire week. Although not completely confirmed, Li suspects that NK cells are boosted by phytoncides, otherwise known as “nice tree smells.” These are essential oils emitted by evergreens and other trees. Li himself uses a humidifier with cypress oil in his house since he found that those who sleep inhaling a cypress scent experience a 20 percent increase in NK cells and less fatigue.
In Korea, where forest bathing is called salim yok, the Forest Agency has established dozens of healing forests with dominant cypress trees. Scientists in Korea confirm the medicinal aspects of phytoncides as antibacterial and capable of “reducing stress 53 percent by lowering levels of cortisol and blood pressure 5–7 percent.” The soil also contains geosmin, which holds streptomyces bacteria, a key to many antibiotics. Two other studies looked at eleven- and twelve-year olds who suffer from “borderline technology addiction” (BTA). After two days in the forest, researchers found lower cortisol levels and improvement in self-esteem. Armed with this research, Korea has planned a National Forest Plan “to realize a green welfare state, where the entire nation enjoys well-being” through work and school programs.
In Finland, economist Liisa Tyrvainen tweaked the experimental design of Miyazaki and concluded that Finns have elevated measures of restoration, vitality, and creativity when walking outside, but they must be in nature at least five hours a month. If you’re outside even longer, “you will reach a new level of feeling better and better,” she concluded.
Singapore is considered one of the top “biophilic cities” in the world. Almost half of the country’s 276 square miles are under some sort of green cover. The population has grown by 2 million; however, the percentage of green space has increased from 36 to 47 percent. Although many of these green spaces are gardens, greenhouses, paths with green corridors, and parks with constructed nature, the government’s vision has succeeded in making this country an oasis in SE Asia. Studies have shown that mortality rates are lower near urban parks.
Other positive health effects of nature: Williams uncovered research in Ohio, Singapore and Australia suggesting that being outside in sunlight stimulates the release of dopamine from the retina, which prevents the eyeball from getting too oblong, thus preventing myopia (nearsightedness).
Awe: According to the author, Irish philosopher Edmund Burke may have understood the effect of transcendent experiences in nature. He traipsed the countryside and found that for something to be “awe-inspiring” there must be “vastness of extent” in which our senses find it difficult to make sense of it—which in turn inspires feelings of humility and a more outward perspective. Dacher Keltner and colleagues at UC Berkeley have found that experiencing awe was the only emotion to significantly lower levels of IL-6, a marker for inflammation. Lower levels are better; higher levels are linked to depression and stress. Keltner also suggests that the emotion awe causes us to reinforce and share emotional connections. Ever wonder why you take those pictures on your cell phones and send them to family and friends?
The book continues by showing how military veterans suffering from Post Traumatic Stress Disorder (PTSD) have diminished symptoms when rafting or backpacking, and how exercise and exploratory play among children increases verbal and math ability, lowers impulsivity, and leads to a threefold decrease in Attention Deficit Hyperactivity (ADHD) symptoms.
Could the positive effects of immersion in nature apply to our educational systems? Yes, indeed. The author states that Germany has more than 1,000 forest kindergartens called Waldkindergarten, where students are out in all kinds of weather. In one instance, after a large tree fell during a storm, the teacher launched a nature-based curriculum in which children sawed off branches to make the tree safe for climbing. In so doing, students practiced dexterity, teamwork and learned about cause and effect. In Scandinavia, 10 percent of preschoolers spend their entire days outside. In Finland, students have recess outside 15 minutes out of every hour. In contrast, two-thirds of the students in this country are Vitamin D (the sunshine vitamin) “insufficient.” In both the U.K. and the U.S.A., rickets, a disease caused by a lack of Vitamin D, has quadrupled in the past 15 years.
The Nature Fix confirms that even small amounts of exposure to the natural world can improve our creativity and enhance our mood. Williams shows how time in nature is not superfluous but is essential to our species. As our modern lives shift dramatically indoors, spending more time in nature is more urgent than ever. As the author succinctly states, “Go outside, often, sometimes in wild places. Bring friends or not. Breathe.”