With increasing rates of stress, anxiety, and other mental health issues, people are looking for new ways to find calm, clarity, and connection. One emerging practice is wood therapy, also known as “forest bathing” or “nature therapy.” Spending mindful, intentional time in natural environments, especially forests, can provide profound benefits for mental, emotional, and physical health. But how exactly does this simple act of being in nature work? What does the science say about the mechanisms behind wood therapy?
A Multi-Faceted Experience
There are many complex reasons why humans find forests and other natural spaces so restorative. These include:
- Phytoncides released by trees, which have demonstrated benefits for immune function and stress reduction.
- Awe inspired by natural beauty and biodiversity. Feeling awe creates positive emotional states.
- Physical movement involved in walking through varied terrain. Movement improves circulation and lowers stress.
- Fresh air from plants’ oxygen production. Deep breathing of clean air brings physiological benefits.
- Soundscape from rustling leaves, birdsong, and other nature noises. Natural sounds are calming for the nervous system.
- Disconnecting from technology and the digital world. Being offline allows the mind to rest and refocus.
- Social connection when done in groups. Humans are social creatures who benefit from community.
These sensory aspects of spending time outdoors in forested areas create shifts in physiology, attention, and mood that allow for relaxation and recalibration. But trees themselves also uniquely contribute to the effectiveness of wood therapy.
Phytoncides – Airborne Chemicals from Trees
Trees and other plants give off organic compounds known as phytoncides or wood essential oils. Evergreen trees such as pine, spruce, and cedar release phytoncides year-round, while deciduous trees have seasonal cycles of release.
When we breathe in phytoncides in forest air, they provide several benefits:
- Strengthened Immune Function: Exposure to phytoncides increases the activity of NK (natural killer) cells, white blood cells that combat tumors and infections in the body. This makes the immune system run more efficiently.
- Reduced Stress Hormones: Phytoncides also decrease production of stress hormones like cortisol and adrenaline, bringing the body into a more relaxed state.
- Lower Blood Pressure and Heart Rate: With less cortisol and adrenaline, heart rate and blood pressure also decrease, promoting cardiovascular health.
- Improved Mood: Boosted immunity, lower stress, and cardiovascular benefits combine to help improve mood and cognitive function.
In essence, breathing in chemicals secreted by trees dials back our fight-or-flight stress response and kickstarts healing mechanisms, inducing a sense of ease.
Forest Bathing: The Optimal Way to Absorb Phytoncides
The term “forest bathing” originated in Japan, where researchers in the 1980s first documented the mental and physical benefits of spending mindful, unstructured time in nature.
Walking slowly through the forest and paying attention to sensory details allows you to fully absorb the phytoncides and benefits that trees provide. Research shows:
- Spending just 15 minutes walking in a forest significantly lowers stress hormone levels.
- After 2-3 hours in the forest, NK immune cell activity increases significantly, lasting for over 7 days.
- The more dense a forest, the higher the concentration of phytoncides, maximizing benefits.
- Morning and evening are peak times for phytoncide production.
Other Healing Mechanisms of Nature
In addition to phytoncides from trees, other mechanisms contribute to improved wellbeing from wood therapy:
- Negative Air Ions: The movement of air and water in natural environments produces negative air ions. When inhaled, these ions boost mood and energy levels by increasing serotonin production.
- Biodiversity: Research finds that people are happier in more biodiverse natural environments, indicating that immersion in abundant plant and animal life contributes to wellbeing.
- Earthing: Walking barefoot on soil, sand, or grass grounds the body electrically and reduces inflammation, resulting in calmer mind states.
Key Takeaways on the Science of Wood Therapy
- Breathing in phytoncides, or essential oils from trees, boosts immunity and lowers stress by decreasing inflammation-producing hormones and chemicals. This induces relaxation.
- The benefits are dose-dependent – the more time spent mindfully immersed in the forest, the greater the gains. Even 15 minutes helps, but a few hours are ideal.
- Biodiversity, negative air ions, movement, fresh air, natural sounds, awe, and digital disconnection also play a role in the healing effects of wood therapy.
- Studies substantiate the measurable biological shifts from spending time in forests, making wood therapy a scientifically-validated therapeutic and preventative health practice.
The Research on Forest Bathing Benefits
While practices like shinrin-yoku have been part of Eastern cultures for centuries, Western medicine is now quantifying the powerful mental and physical health benefits. Here is an overview of the research:
Boosted Immune Function
- A 2010 study had 12 healthy male subjects spend 3 nights/2 days in forested and urban environments. In the forest, their NK immune cell activity increased by 50% on average.
- In 2015, researchers measured a 40% increase in NK cell activity in forest environments compared to city environments among both male and female subjects. The improved immunity lasted a week after the forest experience.
- Children with asthma sent to a forest camp for 4 nights had a 100% increase in NK cell activity.
- After 3 days/2 nights in forested environments, study participants had lower cortisol (stress hormone) levels than after the same time in urban settings. This was true for both men and women.
- In stressed individuals, a forest bathing trip lowered cortisol levels by 24% compared to a city tourist visit.
- Beyond cortisol, forest environments reliably lower blood pressure, heart rate, sympathetic nerve activity, and adrenaline levels, compared to urban settings.
Relief from Depression and Anxiety
- A 2011 study found lower anxiety, depression, anger, fatigue, and confusion in a group asked to sit and view a forest scene, compared to sitting in front of a concrete building.
- A 2015 study had anxious students walk through forested or downtown areas. The forest walks resulted in significantly lower anxiety, heart rate, and heart rate variability compared to urban walks.
Improved Energy and Sleep
- Studies find increased energy and decreased fatigue from spending time in forests versus cities. This is likely due to lowering stress hormones.
- Nighttime wood therapy has been found to result in deeper, more restorative sleep when done during the day prior.
- Hospital patients recovering from surgery who had a daily hour of forest therapy recovered faster with better mobility and fewer pain medications needed compared to staying in their rooms.
- Alzheimer’s patients in care facilities showed improved cognitive function and reduced behavioral symptoms after engaging in forest therapy. The effects lasted for over a month.
- For cancer patients undergoing chemotherapy, a two-hour forest bathing session once a week for 12 weeks resulted in improved immune function versus a control group, enhancing their ability to fight cancer.
Best Practices for Wood Therapy
Here are some key recommendations for maximizing the healing effects and science-backed benefits of wood therapy:
- Seek out forests dense with large trees, which produce more phytoncides. Evergreen forests offer benefits year-round.
- Allow time. Longer forest bathing sessions from 2-5 hours are ideal for unwinding fully. But even 20 minutes can be renewing.
- Practice mindful awareness through all your senses while walking at a slow, relaxed pace.
- Breathe deeply to take in a high volume of phytoncides and negative air ions.
- Leave technology behind to disconnect from disruptive influences. Avoid using electronics in the forest.
- Consider going barefoot to “earth” while walking on dirt paths. Walking on uneven terrain engages the body.
- Drink pure forest air water from streams or springs. Hydrate with the liquid essence of trees for added benefits.
- Journal, meditate, or create art inspired by the forest. Expressive activities deepen the experience.
Wood Therapy for the Future
With highly pressured modern lifestyles, wood therapy offers a profound yet simple way to improve mental, emotional, and physical wellbeing through reconnecting with nature. The science clearly demonstrates the benefits of spending mindful, relaxing time in forested areas. Integrating wood therapy into routines, whether through brief visits to a community forest preserve or half-day hiking excursions, provides natural stress relief and health benefits with minimal cost or technology needed. As more research substantiates the healing power of trees, spending time surrounded by and breathing the essence of living forests will only grow in popularity as an accessible route to better health.