To prove it, Miyazaki has taken more than 600 research subjects into the woods since 2004. He and his colleague Juyoung Lee, also of Chiba University, have found that leisurely forest walks, compared with urban walks, yield a 12.4 percent decrease in the stress hormone cortisol, a seven percent decrease in sympathetic nerve activity, a 1.4 percent decrease in blood pressure, and a 5.8 percent decrease in heart rate. On subjective tests, study participants also report better moods and lower anxiety.

As Miyazaki concludes in a 2011 paper, “This shows that stressful states can be relieved by forest therapy.” And the Japanese eat it up, with nearly a quarter of the population partaking in some way. Between 2.5 million and five million visitors walk the Forest Therapy trails each year.

The science is so convincing that other countries are following Japan’s lead in studying and promoting nature as a cure. Lee just got hired away by the South Korean government, which is pouring more than $140 million into a new National Forest Therapy Center, expected to be completed in 2014. Finland, an empire of boreal spruce and pine, is also funding numerous studies. “Japan showed us that there could be cooperation between forestry and medical fields,” says Liisa Tyrvainen of the Finnish Forest Research Institute. “Now we are conducting similar research.”

I met up with Miyazaki at the country’s newest proposed therapy site, Juniko, a leafy network of trails and lakes near northern Japan’s Shirakami Mountains. The scientist was swatting mosquitoes from his face and neatly trimmed gray hair. In fact, he wasn’t looking relaxed at all. He was worried that the trail might be too muddy for his latest experiment, which would inaugurate the new field version of a brain-oxygen measuring, near-infrared spectrometer. He was kicking rocks out of the way and overseeing the setup of a netted, canopied mini-lab. The next morning, he and Lee would bring 12 male college students here, to measure their brain activity and vital signs after walking and sitting and generally forest bathing. They’d repeat the experiment in downtown Hirosaki, a city of 175,000 about two hours away. I would serve as one of Miyazaki’s stressed guinea pigs.

With the details worked out, several of us retired to a quiet restaurant across from Hirosaki’s Dormy Inn. We removed our shoes and sat cross-legged on the floor while Miyazaki distributed a baffling array of dishes involving runny eggs, seaweed, and gelatinous balls.

“Why do the Japanese think about nature so much?” I asked Miyazaki, who was preparing to eat his modest slab of manta ray.

“Don’t Americans think about nature?” he asked me.

I considered. “Some do and some don’t.”