Everyone knows the basic idea: go for a walk in nature and you’ll feel better. Simple. But is there anything scientific that backs this up?
It turns out, yes—quite a lot.
Dr Qing Li and his research teams in Japan have spent years studying forest bathing (shinrin-yoku) and its therapeutic effects on human health. I’ve always believed that stepping into the woods feels different—that forest air has its own kind of medicine. What I didn’t realise until diving into Dr Li’s work is just how strongly science agrees.
Japanese researchers have documented the impact of simply being in the forest. As Dr Li explains, “Shinrin-yoku means bathing in the forest atmosphere, or taking in the forest through our senses.”
It’s not hiking. It’s not exercise. It’s not even mindfulness.
It’s just being present in nature—and the body responds in remarkable ways.
The Data
One of the most fascinating findings is how dramatically the immune system responds to forest air. In one study of middle-aged office workers, a weekend in the woods boosted natural killer (NK) cell activity by 53%. These are the immune cells that help fight viruses. Even better, levels of anti-cancer proteins—granulysin (helps trigger death in infected or abnormal cells) and granzymes (act like a “cellular assassin,” clearing dangerous cells safely)—increased by 28–48%. And this wasn’t a short-lived effect. The immune boost lasted more than seven days, and in some cases up to 30 days after returning home.
A monthly forest session could realistically keep your immune system in a consistently elevated, healthier state.
Dr Li’s studies consistently show that forest bathing:
- reduces cortisol, our long-term stress chemical
- lowers adrenaline and noradrenaline (the body’s main stress hormones)
- calms the sympathetic nervous system (fight-or-flight)
- activates the parasympathetic system (rest-and-recover).
In simple terms, the woods help your body remember how to breathe again as it doesn’t just make you feel relaxed—it actually changes your body’s stress chemistry and nervous system activity.
One of my favourite stats comes from a study where participants spent a day in a forest park. Their cortisol levels dropped significantly, and mood scores improved across the board—anxiety, depression, anger, tension and fatigue. As Dr Li notes, “The effect on mental stress was greater than on physical stress.” People experiencing depression often show an even stronger response. In one study, a single day in the forest produced significant improvements in mental health.
Impact on modern lifestyle diseases
High blood pressure is one of modern life’s silent burdens. Forest bathing appears to ease that too. In one study, both systolic and diastolic blood pressure dropped by 7mmHg after a forest walk, with no improvement at all in the city environment.
It also doesn’t surprise me that shinrin-yoku improves sleep. Multiple studies show that time in nature:
- helps people wake feeling more refreshed
- improves sleep quality
- increases serotonin levels
- boosts energy and reduces fatigue.
Dr Li has suggested that forest air could support better immune resilience, thanks to its combined stress-reducing and immune-boosting effects. When you look at the full body of research, Shinrin-yoku has documented potential benefits for:
- hypertension
- cancer prevention
- heart disease
- diabetes
- depression
- sleep disorders
- stress-related illness
Here’s the part I find most magical: the forest itself actively helps us heal.
One of the most fascinating parts of forest bathing is how the trees themselves seem to help us. Forests release aromatic compounds called phytoncides - α-pinene and limonene—natural oils trees use to protect themselves. Researchers have measured exactly how these chemicals affect humans. Volunteers either walk through forests or breathe controlled doses of phytoncides in lab settings. Scientists then check stress hormones like cortisol, adrenaline, and noradrenaline, and test immune markers such as natural killer (NK) cells and anti-cancer proteins. The results are striking: exposure lowers stress hormones, boosts immune activity, and improves mood. In other words, just by breathing, the forest is giving your body a gentle tune-up.
You don’t need to trek into a remote forest to benefit. Even city parks can reduce anxiety, depression, anger, fatigue and confusion. Patients recovering from strokes or surgery also show emotional and physiological improvements when exposed to greenery or forest-like gardens.
Nature doesn’t need to be perfect to work.
It just needs to be present.
Why This Matters Now
Most of us are living with more screens, more noise and far less nature than any generation before us. Chronic stress and lifestyle-related illnesses are rising, and many people feel disconnected—from themselves and the world around them.
Forest Medicine offers something radically simple:
Go outside. Slow down. Let the forest air do what it has always done.
As Dr Li writes, “Shinrin-yoku may have potential preventive effects on non-communicable diseases", which develop due to a combination of genetic, lifestyle, and environmental factors.
And honestly, the idea that health, clarity and calm might be waiting for us beneath the trees feels like the kind of wisdom we’ve always known—science is simply catching up.
References:
Effects of forest environment (Shinrin-yoku/Forest bathing) on health promotion and disease prevention —the Establishment of “Forest Medicine”— Dr. Qung Li, National Library of Medicine, accessed via https://pmc.ncbi.nlm.nih.gov/articles/PMC9665958/#sec5