Forest bathing is the practice of slowly and intentionally immersing yourself in a forest environment, using all five senses to absorb the surroundings. It’s not hiking, exercising, or foraging. The idea is simply to be present among trees. The term comes from the Japanese phrase “shinrin-yoku,” coined in 1982 by Akiyama Tomohide, then Director General of Japan’s Forestry Agency, who wanted to encourage people to visit forests for relaxation and enhance the perceived value of Japan’s woodlands.
Since then, researchers have studied what actually happens in the body during and after time spent in forests, and the findings go well beyond “it feels nice.” Forest bathing measurably lowers stress hormones, shifts the nervous system toward a calmer state, and boosts immune cell activity that persists for weeks.
What You Actually Do
A forest bathing session looks nothing like a nature hike. There’s no destination, no pace to maintain, no distance goal. You walk slowly through a wooded area, pausing often. You might sit against a tree, listen to birdsong, watch light filter through leaves, or notice the smell of soil and bark. The practice emphasizes sensory engagement: the texture of moss, the sound of wind moving through branches, the feel of cool air on your skin.
Sessions typically last one to three hours, though even shorter visits produce measurable effects. In Japanese studies, day trips to forest parks were enough to significantly lower blood pressure and cortisol while boosting immune function. The key ingredient isn’t duration so much as presence. Phones stay in pockets. Conversation, if you’re in a group, is minimal. The goal is quiet, unhurried attention to the natural environment around you.
How It Affects Stress and Heart Health
A large field study across 24 forests in Japan found that spending time in forest environments lowered salivary cortisol (the body’s primary stress hormone) by about 13 to 16 percent compared to spending the same time in a city. That drop happened whether people were sitting and looking at the forest or walking through it.
The cardiovascular effects are equally consistent. In the same study, systolic blood pressure dropped by about 2 percent in the forest compared to the city. Other research found more dramatic reductions: a 7 mmHg drop in both systolic and diastolic blood pressure after walking in a forest park versus an urban area. For context, a 7-point drop in systolic pressure is roughly what some people achieve with a single blood pressure medication.
Heart rate tells a similar story. Forest walking produces a significantly lower heart rate than urban walking, about 4 to 5 fewer beats per minute. More importantly, forest environments shift the balance of the autonomic nervous system. Parasympathetic activity (the “rest and digest” branch) increases significantly, while sympathetic activity (the “fight or flight” branch) decreases. This isn’t just relaxation in the colloquial sense. It’s a measurable shift in how the nervous system regulates the heart, digestion, and stress response. That shift begins within the first few minutes of walking and persists throughout the session.
The Immune System Response
One of the most surprising findings involves natural killer cells, a type of white blood cell that identifies and destroys virus-infected cells and tumor cells. After multi-day forest bathing trips, participants showed increased natural killer cell activity that lasted more than 30 days. Even single day trips to a forest park significantly boosted these cells, with the effect persisting for about seven days.
The mechanism involves volatile organic compounds that trees and plants release into the air, sometimes called phytoncides. These airborne chemicals, which give forests their distinctive smell, appear to stimulate immune cell production and activity. Trees release them as part of their own defense system against insects and disease, but when humans inhale them, the compounds trigger a cascade that enhances immune surveillance.
Researchers who studied this effect suggested that a forest bathing trip once a month could be enough to maintain elevated natural killer cell activity on an ongoing basis.
Mental Health and Mood
Forest bathing produces broad improvements across every negative mood dimension researchers have measured: anxiety, depression, anger, fatigue, and confusion all drop significantly after a session. What’s particularly striking is how the benefits scale with need. People who start with higher levels of distress experience the largest improvements.
In a study comparing people with depressive tendencies to those without, both groups saw significant mood improvements after forest bathing. But the group with depressive tendencies improved so much that their anxiety, anger, fatigue, and confusion scores dropped to levels statistically indistinguishable from the non-depressed group. Their tension and anxiety scores improved by nearly twice as much as the scores of people who started in a better mental state. In other words, forest bathing didn’t just take the edge off. For participants who were struggling most, it essentially closed the gap.
There’s also a cognitive dimension. The concept known as Attention Restoration Theory suggests that natural environments replenish a mental resource that urban life steadily drains. Concentrating in a busy, stimulating environment (screens, traffic, noise, decisions) requires what psychologists call directed attention, and that capacity fatigues. Natural settings engage a different, effortless kind of attention. The rustle of leaves, the pattern of branches, the movement of water: these hold your interest without demanding focus, giving the directed attention system a chance to recover.
Forests vs. Urban Parks
If you don’t live near a forest, you might wonder whether a city park offers similar benefits. The answer is: some, but not as many. A study comparing walking in a forest park to walking in an urban park found that the forest produced lower systolic blood pressure by about 5 mmHg, lower heart rate by about 2.5 beats per minute, and reduced cardiac output compared to the urban park. Both settings were better than sitting indoors, but forests had a clear physiological edge.
This likely comes down to the density of trees, the concentration of plant-released compounds in the air, the reduction in noise, and the absence of urban stimuli. A manicured city park surrounded by traffic doesn’t offer the same sensory environment as a canopy of trees filtering light and sound. That said, urban greenspace still provides measurable stress reduction, so a city park is a reasonable substitute when a forest isn’t accessible.
Staying Safe Outdoors
Forest bathing involves slow movement and sitting in natural areas, which means prolonged exposure to ticks, particularly during warmer months from April through September. Treating clothing with permethrin before your session provides protection that lasts through several washes. Applying an EPA-registered insect repellent containing DEET or picaridin to exposed skin adds another layer of defense. If you’re also applying sunscreen, put that on first.
After your session, shower within two hours, which has been shown to reduce the risk of Lyme disease by washing off ticks before they attach. Do a full-body check, paying attention to areas ticks favor: behind the ears, along the hairline, behind the knees, around the waist, and between the legs. Toss your clothes in the dryer on high heat for at least 10 minutes to kill any ticks that hitched a ride home.
People with pollen allergies or asthma may find that certain forests trigger symptoms, especially during spring and early summer. Choosing conifer-dominant forests (pine, cedar, spruce) outside peak pollen season, or visiting after rain when pollen counts drop, can make the experience more comfortable. Starting with shorter sessions lets you gauge your body’s response before committing to a longer outing.