Research conducted over the last 30 years demonstrates that forest bathing is not only one of the most accessible ways to get in touch with the natural world, but also one of the most simple ways to lower excessive stress levels The Japanese authors of the Therapeutic Effects of Forests document the physiological measurements of autonomic nervous system activity and show how stress levels can be reduced through walks in a forest. Results confirm that participants who walked in a forest versus those who walked in an urban environment had a more activated parasympathetic nervous system, which allows the body to adapt and recover from stress. Participants also displayed a less activated sympathetic nervous system, the mechanism responsible for triggering the “fight or flight” stress response Field studies show that salivary cortisol concentration is significantly lower in those who participated in forest bathing when compared to those exposed to an urban environment. Several previous studies have demonstrated that lower levels of stress result in lower concentrations of cortisol.
There are several components of forest bathing that provide stimulation to the senses and contribute to stress reduction: the smells, sights, sounds, tastes and textures of the forest all promote healing in unique and seemingly subtle ways. Phytoncides, the essential oils trees emit to protect themselves from germs and insects, can be emitted from many types of plants, trees, and some fruits and vegetables, and can decrease cortisol, reduce anxiety, increase pain threshold, increase natural killer cells, lower blood pressure, and have antibacterial properties. Research demonstrates that nature sounds, such as birds chirping and running water, promote sympathetic nervous system recovery after a stressful incident more quickly than urban environment sounds. Electroencephalogram (EEG) data indicates that subjects who viewed nature "had greater brain electrical activity in the alpha frequency range. High alpha amplitude is associated with lower level of physiological arousal as well as feeling of wakeful relaxation” (Berto, 2014, p.400). Psychologist, researcher and architect Roger Ulrich's infamous study on postoperative gallbladder surgery patients demonstrated that patients with a view of nature from their hospital window recovered quicker, were in less pain and were described by nurses’ as having better a attitude than patients who had a view of a brick wall (Ulrich, 1984).
Tsunetsugu et al. (2010) report on previous work, which shows how interior and wooden objects elicit favorable emotional responses compared to other natural or man-made materials. Mao et al. (2012b) also investigated the qualitative properties of wood experienced by participants and found positive reactions. Researchers, therefore, hypothesize that the touch and feel of wood within the forest environment is also likely to contribute to the overall impact of forest bathing.
By opening up all fives senses in nature, the physiological responses of the human body can promote recovery from stressful situations.
Stress regulation has a tremendous impact on an individual’s overall health and wellbeing. Our perception of stress, our mental state, our immunity, our happiness, and our resiliency are all chemically influenced by the nervous system and its response to the natural environment.The Therapeutic Effects of Forests study provided additional research that forest bathing can significantly lower levels of systolic and diastolic blood pressure. Further physiological benefits of spending time in nature include increased serotonin levels, decreased feelings of anger, a greater sense of joy and happiness, increased activity in parahippocampal gyrus region of brain, and improved quality of sleep. Research supports that time spent in nature can lower inflammatory markers, increase natural killer cells and anticancer proteins by up to 40%, that hospital patients with view of nature heal quicker than those with view of a brick wall, sunlight exposure increases white blood cell production, which boosts immune system and red blood cells, and can also increase one’s oxygen-carrying capacity.