When my editors asked me to report on forest bathing, I packed a swimsuit. I assumed it must involve a dip in the water.
It turns out, my interpretation was too literal.
I met certified Forest Therapy guide Melanie Choukas-Bradley and several other women who'd come along for the adventure at the footbridge to Theodore Roosevelt Island, a dense jungle of an urban forest along the Potomac River in Washington, D.C.
Here, I began to get it. Forest bathing isn't a bath. We sat on the banks of the river, but we did not get in the water.
It's not a hike, either. We did walk the forest trails, but we meandered with no particular destination in mind.
The aim of forest bathing, Choukas-Bradley explained, is to slow down and become immersed in the natural environment. She helped us tune in to the smells, textures, tastes and sights of the forest. We took in our surroundings by using all our senses.
As we passed through a stand of pawpaw trees, we touched the bark. We smelled the black walnuts, which give off a lovely citrus fragrance. We got a little shower of ripe mulberries, too.
"Close your eyes and just breathe, just breathe," Choukas-Bradley intoned. It felt a bit like a meditation retreat.
It took me a few minutes to clear out the clutter in my brain, and tune in to the natural world.
"When you open your eyes, imagine you're seeing the world for the very first time," Choukas-Bradley told us.
After I opened my eyes, the green looked a lot greener. And I began to see things I hadn't noticed before: the flutter of birds, the ripple of the water, the swaying of trees.
A forest guide "helps you be here, not there," says Amos Clifford, a former wilderness guide with a master's degree in counseling, and the founder of the Association of Nature & Forest Therapy, the organization that certifies the guides.
Clifford's goal is to encourage health care providers to incorporate forest therapy as a stress-reduction strategy. There's no question that stress takes a terrible toll in the United States; a 2015 study found work-related stress accounts for up to $190 billion in health care costs each.
"It's my hope that the health care system will include [forest therapy] into the range of services they reimburse for," Clifford says.
The practice began in Japan. Back in the early 1990s the Japanese Ministry of Agriculture, Forestry and Fisheries coined the term Shinrin-yoku — which translates roughly as forest bathing.
Now, forest bathing is starting to take off in the U.S. The Association of Nature & Forest Therapy plans to train and certify about 250 new guides next year. "We're aiming to have 1,000 trained guides within three years," Clifford says.
There's a growing body of evidence that the practice can help boost immunity and mood and help reduce stress. "Medical researchers in Japan have studied forest bathing and have demonstrated several benefits to our health," says Philip Barr, a physician who specializes in integrative medicine at Duke University.
One study published in 2011 compared the effects of walking in the city to taking a forest walk. Both activities required the same amount of physical activity, but researchers found that the forest environment led to more significant reductions in blood pressure and certain stress hormones.
On average, the forest walkers — who ranged in age from 36 to 77 — saw a reduction in their systolic blood pressure from 141 mmHg down to 134 mmHg after four hours in the forest.
This might not sound like a big difference, but it can be clinically significant. Most doctors these days agree that people younger than 60 should aim to keep their blood pressure under 140.
"I'm very impressed with the primary research done in Japan," Barr says. He thinks many patients could benefit from forest bathing, especially those who are under stress.
"Forest bathing could be considered a form of medicine," Barr says. "And the benefits of nature can be accessed so simply."
It's not a big surprise that researchers were able to document a decrease in blood pressure among forest bathers. As people begin to relax, parasympathetic nerve activity increases — which can lead to a drop in blood pressure.
There's another factor that might help explain the decline in blood pressure: Trees release compounds into the forest air that some researchers think could be beneficial for people. Some of the compounds are very distinctive, such as the scent of cedar. Back in 2009, Japanese scientists published a small study that found inhaling these tree-derived compounds — known as phytoncides — reduced concentrations of stress hormones in men and women and enhanced the activity of white-blood cells known as natural killer cells .
Another study found inhalation of cedar wood oils led to a small reduction in blood pressure. These are preliminary studies, but scientists speculate that the exposure to these tree compounds might enhance the other benefits of the forest.
The idea that spending time in nature is good for our health is not new. Most of human evolutionary history was spent in environments that lack buildings and walls. Our bodies have adapted to living in the natural world.
But today most of us spend much of our life indoors, or at least tethered to devices. Perhaps the new forest bathing trend is a recognition that many of us need a little nudge to get back out there.
DAVID GREENE, HOST:
Ninety-nine-point-nine percent of our evolutionary history was spent in natural environments. Our bodies are simply adapted to being in nature. But today we are spending most of our lives indoors - you know it - tethered to our devices. Well, now a practice that started in Japan that's aimed at reconnecting us with nature is beginning to take off here in the U.S. It is known as forest bathing. As NPR's Allison Aubrey reports, there's growing evidence its benefits may be just what the doctor ordered.
ALLISON AUBREY, BYLINE: It turns out there's actually a certified forest bathing guide right here in Washington, D.C. Her name is Melanie Choukas-Bradley. I met up with her on a lush jungley (ph) island in the Potomac River.
MELANIE CHOUKAS-BRADLEY: I'm totally in love with this island.
AUBREY: It's just a footbridge away from the busyness and noise of the nation's capital.
CHOUKAS-BRADLEY: This is our challenge here. We're right under the Reagan National flight path.
AUBREY: As we step on the trail, everything on this island is green and blooming.
CHOUKAS-BRADLEY: So this is the place where we're really going to begin our forest bathing.
AUBREY: Along the narrow trail, we pass under a canopy of pawpaws, then black walnut trees. And we get a little shower of ripe mulberries.
CHOUKAS-BRADLEY: Aren't they beautiful just looking up at the black against the green and the red?
AUBREY: Now, given the term forest bathing, I thought we might be taking a dip in the water, so I've packed my swimsuit. But it turns out my interpretation was way too literal.
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AUBREY: Melanie gathers us in a circle and invites us to immerse ourselves in what she calls the pleasures of presence.
CHOUKAS-BRADLEY: If you'd like to close your eyes and just breathe this wonderful cool air, just breathe. Just breathe.
AUBREY: So now I'm beginning to get it. Forest bathing is sort of like a cross between a hike and a meditation class, except there's no destination. The aim here is to slow down and immerse yourself in the forest, tune into its sights, its smells, its textures.
CHOUKAS-BRADLEY: And when you feel ready, open your eyes and imagine you're seeing the world for the very first time.
AUBREY: Suddenly the green looks a lot greener, and I start to see things I hadn't noticed before - the flutter of birds, the ripple of the water, the swaying of the trees.
CHOUKAS-BRADLEY: I can hear some summer insects and a bird up in a tree nearby.
AUBREY: As we walk on, Melanie stops us at a bush. I would have just passed by.
CHOUKAS-BRADLEY: If you want to just come scratch this twig of this spice bush and smell it, it's very yummy.
AUBREY: To me, it smells like cinnamon or bay leaf. It's warm and earthy.
CHOUKAS-BRADLEY: Isn't that nice?
AUBREY: There's a whole world of fragrance in the forest. Think of the smell of pine and cedar trees.
CHOUKAS-BRADLEY: There's been a lot of research about the healthy volatile compounds that trees release and how good they are for our own health.
AUBREY: Now I should point out that when my editors asked me to do a story about forest bathing, I did a little eye roll. It sounded so hokey to me. But it's turned out to be a pretty powerful experience, and I wanted to know if it's really doing something good for my health.
PHILIP BARR: As a matter of fact, medical researchers in Japan have specifically studied forest bathing and demonstrated several benefits to our health.
AUBREY: That's Philip Barr. He's the lead physician at the integrative medicine center at Duke University. He reviewed the studies for us, and he says they document a range of effects.
BARR: From lowering blood pressure and heart rate, lowering stress hormones, raising immunity and in general allowing the whole body to be in a more relaxed, healing state.
AUBREY: Barr says he thinks a lot of his patients could benefit from forest bathing, especially people dealing with a lot of stress.
BARR: Absolutely forest bathing could be considered a form of medicine.
AUBREY: And as I just discovered, the National Park Service has already rolled out its park prescription program. The aim is to help health care providers get their patients out into nature.
GREENE: Allison Aubrey's voice there. She was reporting. And she is fresh off her forest bathing experience in our studios. Hey, Allison.
AUBREY: (Laughter) Oh, still feeling so relaxed. Hey there, David.
GREENE: Still feeling mellow. You sound mellow. Am I allowed to be depressed that someone has to fill out a...
GREENE: ...Prescription to go out into nature? I mean is that where we've come?
AUBREY: I hear you, David. I think Henry David Thoreau might be turning over in his grave (laughter), right?
GREENE: Yeah, I'd say so.
AUBREY: I think it's this idea that a retreat to nature gives us stillness and calm. It's age old. We all already know it, right? I think that, as you mentioned in the introduction to the story, we are tethered to our devices. I mean many of us are just so disconnected from the natural world that I think we may need help or a little nudge just to learn how to hang out. I think that's the point of having a guide in forest bathing. It might be why it's taking off. You know, just like you have a yoga teacher to do yoga, a guide in the forest can help people slow down enough to really immerse themselves in the natural environment.
GREENE: So but let's be clear here, Allison. I could actually get forest bathing on my health care plan potentially.
AUBREY: Well, not yet, but the founders of this movement hope that that's coming. I mean if you think about the toll of stress in our lives - one recent study estimated that workplace stress is linked to about $150 billion in health care costs a year. So if something as simple as being in nature is a good antidote to stress, health care providers might want to think about this.
GREENE: No disrespect to forest bathers, but couldn't I just go take a walk?
AUBREY: (Laughter) Good question. I mean I think any kind of exercise can help with stress relief. It's very well-documented. But the Japanese scientists studied this in a really clever way I think. What they did is they had people walk in an urban area in Tokyo for a few hours. And then a week later, they had them walk in the forest. Now, both of these walks required the same amount of physical activity, but what they found is that the forest environment led to more significant drops in stress hormones and blood pressure. And so that kind of gives you a sense of the scope.
GREENE: What else - you did mention I mean speaking about the difference between city and forest - there are these compounds that the trees give off that can really be good for us.
AUBREY: Yeah, you know, it sounds a little wacky, but trees have these essential oils that give off fragrances - so, you know, those cedar and pine smells. And they also have all these other compounds that they release into the air. And when we breathe them in, it turns out there may be some benefit to us as well. I'd say it's still pretty speculative. But one of the Japanese studies found that just breathing in this forest air compared to what they called blank air actually led to a small decrease in blood pressure on its own.
GREENE: Blank air being like what we're breathing in right now in an office you're saying.
AUBREY: That's what I'm assuming, sort of...
AUBREY: ...Blank air, office air.
GREENE: Well, sad that we're both breathing blank air...
GREENE: ...Today. We should get out and do some forest bathing.
AUBREY: Here's to breathing more forest air and less blank air.
GREENE: There you go. NPR's Allison Aubrey. Thanks, Allison.
AUBREY: Thanks, David. Transcript provided by NPR, Copyright NPR.