How Does Forest Therapy Benefit People?
By Dr Christine Carroll
Forest therapy is a form of guided outdoor restorative practice inspired by the Japanese practice of shinrin-yoku, or “forest bathing,”. A forest therapy session typically involves trained instructors slowly guiding people through a natural environment while inviting them to immerse themselves in nature through all of their senses. The practice of Forest Therapy is open-ended, with no predetermined outcome. It focuses on nurturing a reciprocal relationship between the forest and the individual. Forest therapy is structured in the form of a clearly defined sequence of guided invitations that allow for creativity and individual difference. Forest therapy encourages individuals to be present in the moment, enjoying the sensation of being alive and connecting more deeply with the rest of the natural world.
Shinrin-yoku started in Japan in the 1980s in response to a national health crisis. Authorities noticed a sharp increase in stress-related illnesses which they attributed to long working hours in areas of technology and other industrial work. Designated forest bathing trails were created to guide people in outdoor experiences. Decades of research show that forest bathing may help reduce stress, improve attention, boost immunity, and lift mood. In this essay I will address some of the many demonstrated benefits of forest therapy.
Stress reduction
According to Stress Reduction Theory (Ulrich,) humans have evolved to develop unconscious and immediate emotional and physiological responses to their environment. When faced with a stressful situation the body’s sympathetic nervous system is triggered. This prompts the release of hormones such as adrenaline and cortisol which stimulate the so-called “Fight or Flight” response. The body prepares itself for immediate action in response to the perceived threat, for example the heart beats faster, pupils dilate, breathing quickens, the liver releases glucose for energy body.
As human society has altered so rapidly over the past few hundred years, the perceived threats to our sense of safety have expanded to include daily hassles of modern life such as work stress, relationship problems, financial worries, status anxiety etc. As a result many of us find ourselves in the position where our stress response is perpetually stimulated resulting in the experience of psychological and bodily illness such as high blood pressure, muscle tension, anxiety and depression.
The relaxing impact of nature has been long documented in the endocrine system. Walking in the forest has been shown to increase parasympathetic nervous activity and reduce sympathetic nervous activity as indicated by reduction in cortisol, adrenaline and noradrenaline levels and increased high frequency component (HF) of heart rate variability (HRV) and decreased low frequency component (LF)/(HF) ratio. In this way Forest Therapy may reduce the likelihood of numerous lifestyle related behaviours which may be exacerbated by stress such as cardiovascular diseases, cancer, gastrointestinal diseases, stroke, obesity and depression.
Immunity
Forest therapy enhances the immune system. Research suggests it does this by promoting exposure to phytoncides and negative air ions. Negative air ions are created in the natural environment by sunlight, moving air, water and radiation. Phytoncides are volatile organic compounds, (VOCS) or “essential oils” given off by trees. These chemicals have natural antimicrobial and insecticidal qualities that protect the tree from germs and parasites. Phytoncides and negative air ions increase natural killer (NK) cell activity. These are white blood cells which destroy infected and diseased cells like cancer cells. They also increase anti-cancer proteins and reduce the level of pro-inflammatory cytokines which trigger or heighten inflammation in the body. While acute inflammation is necessary and helpful for fighting infection, chronic inflammation is harmful causing damage to normal cells , reducing immunity and increasing the risk of disease.
Forest therapy also increases our exposure to diverse microbiota. Microbes exist in the natural environment in soil, trees, air and water. Walking through nature we can inhale these microbiota which can attach to our skin , respiratory system and gut. It has been demonstrated that these microbes can regulate our immune systems and are vital for our health. They may also impact on our susceptibility to allergens.
Attention and Mood
Forest therapy has also been demonstrated to have a positive impact on mental processes including enhancing attention and mood. Attention Restoration Theory (ART) is a psychological theory that spending time in nature, or even looking at depictions of nature can counteract mental fatigue and help people to concentrate better. The theory was developed by Rachel and Stephen Kaplan in the 1980s in their book “The Experience of Nature: a Psychological Perspective” and has since been validated in both clinical and academic studies. The theory asserts that natural environments provide aesthetic, yet intellectually unimportant stimuli or “soft fascinations” which allow the mind to sit in the “default mode network” and take a break from the constant evaluation and prioritisation of mental information. This in turn provides an opportunity for the replenishment of the mind’s ability to focus and pay attention. The theory advises a number of necessary characteristics for an environment to be restorative including providing the feeling of “Being Away”, the generation of awe or “Soft Fascination”, the feeling that one can travel further into the environment “Extent” and personal “Compatibility” with it.
Mental health
Spending time in the forest has been shown to improve individuals mood and general mental functioning. A study conducted by Stanford University demonstrated that walking in nature increased positive thinking and stopped subjects ruminating on potential problems. Students were asked to take a series of memory tests and assessments of mood before setting off on a walk. Half of the students went to a leafy tree filled area, the other half walked along a road with busy traffic and both sets of students were assessed again when they came back. Results showed that walking in nature alleviated feelings of anxiety for these students and increased positive thinking.
Other studies carried out by Qing Lee (one of the main proponents of forest therapy research) have demonstrated improved mood states in forest therapy participants as measured by the profile of mood states (POMS) questionnaire.
Research suggests that nature contact activates the brain reward circuitry. Kim et al (2010) using fMRI reported that viewing images of nature, compared to images of urban landscapes, predominantly activates the anterior cingulate gyrus, globus pallidus, putamen and caudate nucleus. These are parts of the brain involved in reward circuitry and are typically activated by stimulation such as pleasurable music and smiling faces. The neural reward circuitry is typically hypoactive in depression. Furthermore reward activates the dopamine neurotransmitter system. Increased dopamine enhances memory and cognitive flexibility.
Forest therapy also increases the amount of direct sunlight exposure. Sunlight is essential for human health. It has been reported that longer duration of exposure to bright sunlight results in a faster rate of production of serotonin, a neurotransmitter essential in mood and emotional regulation. Lack of serotonin is considered to contribute to mood disorder. Exposure to sunlight may increase the production of serotonin through increased synthesis of vitamin D in the skin or through direct stimulation of retinal ganglion cells.
Forest therapy typically involves engaging in mindfulness-based invitations. Mindfulness is the ancient practice of gently focusing your awareness on the present moment, while calmly acknowledging and accepting thoughts, feelings and experiences. Over time mindfulness practice can improve your ability to let your thoughts come and go freely without obeying them, or struggling against them. This can help you to stay focused on the present moment and more fully appreciate the here and now. Practicing mindfulness has been shown to reduce anxiety and stress and reliably enhance physical and mental well-being.
Practicing mindful activities in a natural environment can also help people to foster a deeper sense of connection with the world around them. Individuals may experience a sense of spiritual nourishment or release from their egoic self.