“Its clear our bodies still recognize nature as our home…”Professor Yoshifumi Miyazaki.
People and trees have lived together for millennia. It’s no secret we feel good around trees and flowers. We know intuitively that we feel better when we’re around the natural world. Curious scientists decided to explore the connection between humans and nature behind the intuitive feelings. In the past sixty years, the relationship between human physiology and nature has been extensively studied, operationalized and quantified.
Japanese researchers began the studies on the effects of the natural world on human physiology and mood. In Japanese culture, spirituality and nature are intertwined: the trees and the forest are considered sacred. Based on the findings of early Japanese studies, the concept of shinrin-yoku, forest bathing, was developed.
The predecessors of the human species spent millions of years on earth, very connected to nature – outside. Homo sapiens have been on earth for 200,000 years. They, too, spent their time as part of the natural world. Human physiology is greatly affected by the sights, sounds, tastes, the feel, the scents of the natural world. But, in the past 70 years – a brief nanosecond in evolutionary time – we’ve moved indoors and now spend lots of time on our sedentary and on screens. On a global scale, we’ve morphed into urban dwellers. In 2016, 54% of the world’s population was recorded as living in urban areas. Technostress, defined as using technology in an unhealthy way, is rampant. The World Health Organization says that anxiety and depression are in the top three leading causes of work related disability worldwide.
It’s important to discover easily accessible stress management techniques, that are fact based and proven to be effective to optimize mental and physical wellness.
Forest bathing is a simple way to manage stress in the mind and body. It’s an evidence-based technique, available in different forms to most people, and requires little effort. One doesn’t need to go to a forest to reap the benefits of nature. Research has shown walking in a city park, or looking at trees from a window, or gardening, or looking at fresh cut flowers is beneficial as well.
Early research on shinrin-yoku, or forest bathing, was conducted in 1990 by Professor Yoshifumi Miyazaki. Stress levels were measured by collecting cortisol in the saliva in people walking mindfully in a forest. With the advent of technological techniques to measure brain activity, more sophisticated research has been conducted involving the collection of data on brain activity and forest bathing. In addition, data has been collected from subjects’ self-report of their subjective emotional state.
All of this collective data shows that time spent in nature has healing benefits. In general, the research has found that two hours a week of time spent in nature is recuperative and restorative. Further research has found that even just looking through a window at a park or at trees or having fresh flowers in the indoor space has positive physical and emotional effects.
On a physiological level, forest bathing down-regulates the nervous system, reduces circulating cortisol, lowers blood pressure, decreases the heart rate, increases the count of natural killer (NK) cells in the immune system and increases the amount of hours of sleep. On an emotional level, forest bathing reduces feelings of tension/stress/irritability and promotes feelings of well being.
Dr. Qing Li’s research finds that being in the forest allows our overstimulated senses to relax. The eyes get to relax as they view objects at a distance, instead of straining to read closely or focus narrowly on a small screen. The ears experience quietude, away from noise pollution, the most common pollution, as there is barely a place on earth that is truly silent today. The olfactory system experiences natural plant scents, that are created by phytoncides.
Phytoncides are natural oils, also called essential oils, that are produced by all plants. Essential oil constituents are phytoncides. There is a wide range of phytoncides, and they have been the subject of much research in the past 75 years. Some of the more well known phytoncide constituents are d-limonene, α-terpineol and linalool. D-limonene is found in citrus rinds and has been used as a food flavoring for centuries. Studies have shown d-limonene to be gently anti-bacterial and have anti-anxiety properties. A-terpineol is found in pine trees. It is widely used in cosmetics and cleaning products. Studies have shown a-terpinol to have anti-hypertensive effect on humans and to be antibacterial. Linalool is found in many plants, and is used extensively in cosmetics. Linalool can be found in lavender and has been shown to have a sedating and calming effect on mood.
There’s alot of research data to back up the health benefits of forest bathing. Forest bathing should be done mindfully, without the distortions of technology …yes, that means take the ear buds out! And turn the phone on silent. Pick a spot, on a hiking trail or in a city park, clean your mind and walk mindfully. Take in the sights, sounds, sells and textures of the plants and trees around you. Get to know the trees and visit them. Forest bathing is a productive self-care method and you are taking of your body and mind!
De Gruyter (2021). α-Terpineol, a natural monoterpene: A review of its biological properties https://doi.org/10.1515/chem-2018-0040
Miyazaki, Y. (2018). Walking in the woods: Go back to nature with the Japanese way of shinrin-yoku. Portland, Oregon: Timber Press.
Li, Q. (2018). Forest bathing is great for your health: here’s how to do it. https://time.com/5259602/japanese-forest-bathing/
Li, Q. (2018). Forest bathing: How trees can help you find health and happiness. London: Penguin Life.
Li Q. (2010). Effect of forest bathing trips on human immune function. Environmental health and preventive medicine, 15(1), 9–17. https://doi.org/10.1007/s12199-008-0068-3
Gen-Xianh Mao MD et al (2012). Therapeutic effect of forest bathing on human hypertension in the elderly. Journal of Cardiology,(60,6,), p. 495-502. https://www.sciencedirect.com/science/article/pii/S0914508712001852
Peterfalvi, A., Meggyes, M., Makszin, L., Farkas, N., Miko, E., Miseta, A., & Szereday, L. (2021). Forest Bathing Always Makes Sense: Blood Pressure-Lowering and Immune System-Balancing Effects in Late Spring and Winter in Central Europe. International journal of environmental research and public health, 18(4), 2067. https://doi.org/10.3390/ijerph18042067
Science Direct (2021) https://www.sciencedirect.com/topics/medicine-and-dentistry/linalool/pdf
Zeng, W. C., Zhang, Z., Gao, H., Jia, L. R., & He, Q. (2012). Chemical composition, antioxidant, and antimicrobial activities of essential oil from pine needle (Cedrus deodara). Journal of food science, 77(7), C824–C829. https://doi.org/10.1111/j.1750-3841.2012.02767.x