For millennia, humans have known how good nature can make us feel; intuitively we know that being immersed in nature has a positive impact on our overall well-being. Be it spending time deep in a forest, or a simple walk through a community park, we seem to feel relaxed, less stressed, and have an improved mood when connected with nature.

Recent research has begun to reveal the scientific basis behind this feeling. Nature can benefit both one's physiological and mental health, and can not only assist in restoring health, but can act in a preventative manner as well.

What is Forest Bathing?

Forest bathing, known as Shinrin-yoku in Japanese, is a healing and preventative medicine technique that restores both physical and mental health through a “five senses experience” in a forest environment. Forest bathing trips are usually short, leisurely visits to forests and are sometimes regarded as being similar to natural aromatherapy.

The practice of forest bathing can differ in immersion techniques, from merely being in the forest atmosphere while anchoring the mind to the present, to engaging in therapeutic and relaxation activities such as visualization techniques, aromatherapy, acoustic therapy, gong baths, and more. Despite variations in the forest bathing approach, the presence of three critical elements is essential to fulfilling an authentic and legitimate forest bathing experience; movement at a slow pace, a connection with the natural world and a focus on the senses.

The History of Forest Bathing

The term Shinrin-Yoku was coined in 1982 by the Agency of Japanese Agriculture, Forestry and Fisheries of Japan. Forest bathing began as a national health program with the aim of combining forest visits with health and wellbeing-oriented tourism. The program focused on encouraging people to frequently escape urban centres and ‘bathe’ in the forest air.

In Japan, the belief that the forest has healing powers is greatly influenced by both official religions; Shinto and Buddhism. Both religions hold the belief that the forest is a divine realm. The Shinto religion asserts that spirits and nature are one and the same, with spirits called kami, living within trees, rocks, water, and the breeze. The religion of Buddhism maintains the belief that scripture is written into the natural landscape with the word of the Gods being seen in all living things.

Beyond Japan, cultures across the globe historically and in the present day practice relationship with the natural world as integral to spiritual practice, health and wellbeing.

Contemporary hypotheses

Various contemporary hypotheses provide support for the healing ability of nature and provide a lens for forest bathing as a practice. These hypotheses, such as Wilson’s Biophilia Hypothesis, the Old Friend’s Hypothesis, the Biodiversity Hypothesis, Ulrich’s Stress Reduction Hypothesis, and Kalpan’s Attention Restorative Hypothesis, may potentially underpin the benefits of immersing oneself in natural environments.

The Biophilia Hypothesis suggests that humans have a biological disposition to seek connections with nature. When this hypothesis was first put forth, there was very little scientific grounding and was more philosophical in nature. Now, researchers are finding that there are health benefits to being surrounded by nature, and the Biophilia Hypothesis continues to be used to support the idea that humans are healthier and happier when connected with nature.

The Old Friends Hypothesis asserts that it is imperative for humans to be exposed to symbiotic microbes during childhood to ensure proper adaptive immunity. Children are primarily exposed to these bacteria through interactions with nature and contact with other humans. The ‘old friends’ that researchers refer to when discussing our evolved immune system are the commensal microbiotas that are transmitted from mother to child and through other familial interactions, organisms from that natural environment, and ‘old’ infections that have persisted for millennia as relatively harmless to mankind.

The Biodiversity Hypothesis states that contact with natural environments enhances the human microbiome, helps to enrich immune balance, and promotes allergy protection. Humans are protected by two layers of biodiversity; the external microbiota that is found in soil, plants, waters and animals, and the inner microbiota found in our gut, skin and airways. The inner layer of microbiota is colonized from the outer layer, and as there is lessened contact with nature, there is a reduction of the composition of human microbiota diversity, and thus increased health problems.

The Stress Reduction Hypothesis claims that being in an unthreatening natural environment reduces stress and improves physiological functioning. It was shown that environmental stress can cause serious stress in urban dwellers while exposure to natural environments favours stress reduction.

The Attention Restoration Hypothesis suggests that mental fatigue and concentration can both be improved by immersing oneself in nature or even by looking at nature scenes.

The physiological benefits of forest bathing

Forest bathing provides a great number of benefits for physiological health, which underpins the potential of forest bathing to enhance the health and well-being of participants

Antioxidant benefits

Researchers have concluded antioxidant benefits can be gained through immersion in forested environments by volatile organic compounds emitted by trees, known as phytoncides.

The research suggests that the inhalation of tree-derived volatile compounds have antioxidative effects on individual’s respiratory tracts. In other words, antioxidant benefits can be gained through the emission and inhalation of volatile organic compounds and essential oils from trees.

Immune benefits

One of the greatest physiological benefits that one can gain from forest bathing is an increase in immune functioning. This increased immune functioning is primarily driven by an increase in natural killer cells. Natural killer cells play a key role in the development of multiple illnesses such as cancer, infections, and autoimmune disorders. The increase in an individual’s natural killer cell count is related to increased immune functioning and decreased disease-related inflammation in the body.

One study reported that the benefits of forest bathing on increased immune function can last up to 30 days after a singular forest bathing session. This suggests that a forest bathing trip once a month would provide individuals with the benefits of a higher natural killer cell count and subsequently, increased immune function.

neuroendocrine benefits

Researchers have found that forest bathing lowers cortisol levels, which is an indicator of stress, thus suggesting that participants in these various studies benefitted from physiological relaxation due to the forested environments.

Similarly, after forest bathing trips, individuals have increased parasympathetic activity (associated with relaxation) and decreased sympathetic activity (associated with stress).

CARDIOVASCULAR BENEFITS

Forest bathing benefits cardiovascular functioning, as seen by the lowering of heart rate of participants of forest bathing programs.

Likewise, the blood pressure of individuals participating in forest bathing programs has been shown to decrease while taking in the atmosphere of the forest, when compared with controls in a city area.

The psychological benefits of forest bathing

Psychologically, forest bathing provides great benefits to individuals’ mental well-being. Engaging in forest bathing has shown positive impacts on a range of categories including levels of depression and anxiety, emotional states, psychological recovery, and attitudes and feelings toward things.

levels of anxiety and depression

Forest bathing, in almost all instances, leads to lowered levels of depression and anxiety, and various studies suggest that forest bathing is an effective intervention in decreasing depression levels among adults.

Common treatments for depression are therapy and/or antidepressant medications. These treatments do have their benefits, though also present disadvantages such as negative side effects and a lack of effective short-term results. In contrast, forest bathing programs demonstrate consistent and positive results for alleviating depressive symptoms and as such, could be used as an alternative or supplementary treatment for depression.

In fact, when compared with no intervention or usual care, those who partook in forest bathing or forest therapy programs had a greater reduction of depressive symptoms. Forest bathing therapy also reduced depressive symptoms more than similar activities that were conducted within a hospital or non-forested area.

Forest bathing is effective in reducing anxiety levels, especially in the short term, and was even noted to have greater effects on anxiety than on depression.

Seeing as the most common mental health problems are anxiety and depression, and approximately one-third of the world’s population is or will be, affected by anxiety in their lifetime, the importance of forest bathing in the reduction of anxiety and depression cannot be understated. Even as little as fifteen minutes per day can help to reduce negative mental health symptoms and could benefit in the reduction of anxiety and depression.

emotional states

Forest bathing reduces stress, improves individual mood and emotional status; increasing positive emotions while keeping negative emotions at bay, or alleviating negative emotions.

The improvement of emotional states is not just limited to neutral mood individuals but was extended to participants who had mild depression, anxiety and PTSD.

degree of psychological recovery

Forest bathing leads to greater psychological restoration and mental relaxation, which leads to more efficient and effective psychological recovery.

Researchers induced mental exhaustion in subjects via demanding brain games. Half the group then took a walk in a natural space while the other half took a walk in an urban environment. The groups then repeated the original cognitively demanding task and upon this retesting, the group that was immersed in nature demonstrated improved accuracy, faster reaction time and a greater number of correct responses when compared with those who were immersed in an urban setting.

Spending time in nature may be associated with a reduction in ADHD symptoms, especially when compared with the same activities conducted in built environments.

Attitudes and feelings toward things

Forest bathing leads to greater levels of awe, and less negative rumination. Forests and nature itself can induce deep relaxation and feelings of awe as seen by an increase in gratitude and selflessness. It was also found that spending time in natural settings decreased negative rumination, which is a hallmark of depression and led to a more positive outlook.

With psychiatric health issues on the rise and the disease burden of mental illness expected by the World Health Organization to increase in the few years, the usefulness of forest bathing on mental well-being is highly beneficial.

As our world grows increasingly disconnected from the natural environment, we need to intentionally re-establish our connection with nature. Individuals do not need to spend extensive amounts of time in forest environments or go deep into natural spaces, but people need to make a conscious effort to incorporate nature into their lives.

Forest bathing and its various benefits can help to create happier, healthier communities and a more health-conscious future that is focused on sustaining health and wellbeing.

The Healing Power of Nature: Forest Bathing