Shinrin-Yoku: The Physical and Mental Health Benefits of Forest Bathing

Pacific Spirit Regional ParkForest bathing, or Shinrin-yoku, is a healing, stress-reducing nature-based therapy. Originally recognized in Japan during the early 1980s, it has been gaining in popularity throughout the world in recent years.

Forest bathing is simple, free, and (according to the findings of many studies) highly effective. It involves simply spending time in the forest, experiencing a natural green environment.

Forest Path 2Forest Bathing Increases Immune Function and Cancer Fighting Ability

Most people intuitively understand that getting out into nature is good for us, and there is mounting scientific evidence to support this notion.The findings of numerous studies suggest that forest bathing may improve the immune system’s effectiveness in general and enhance the body’s ability to fight cancer in particular.

Trees emit phytoncides, which are chemicals that protect them against insects and rotting agents, and these chemicals can also help humans fight off disease. Studies have shown that Phytoncides taken from a Cypress tree increased natural killer (NK) immune cells (which can cause tumor and virus-infected cells to self-destruct) and anticancer proteins not only in a petri dish, but also in human subjects exposed to the molecules using a vaporizer.

Forest Nurse LogResearchers in Japan found that NK cells were increased by 40% in study participants who spent time hiking in the woods, and their NK counts were still 15% higher a month afterwards. Those who engaged in urban walking did not receive the same benefits.

Increasing the number of NK cells is particularly important for older individuals and those who are suffering from stress because aging and stress can reduce populations of these immune system defenders.

ForestExposure to Nature Improves Physical Health

Studies and anecdotal evidence provide support for the physical health benefits of spending time in green environments:

    • Diabetics in their early 60s who participated in a forest bathing study had reduced blood glucose levels after spending time in nature.
    • In the past century, there were multiple reports of tuberculosis cures in forest-based sanatoriums.
    • A large study (250,782 participants) found that the percentage of green space in living environments was positively correlated with self-reported health, regardless of age or socioeconomic status.

Forest PathMoreover, there is evidence that simply viewing green spaces or greenery, even when indoors, can have health benefits:

    • A 2011 study found better self-reported health among cardiopulmonary patients who had nature views.
    • A Michigan prison study found that inmates with nature views were less likely to require medical attention.
    • A Norwegian study found that having plants in an office reduced the likelihood that employees would take sick leave.
    • A Japanese study found that adding plants to the classroom reduced high school students’ visits to the infirmary.

Forest TrailGreenery Can Reduce Pain and Speed Recovery

Studies have also shown that exposure to nature can diminish physical pain and speed recovery from illness or injury:

    • A study of patients recovering from surgery at a Pennsylvania hospital found that those with a forest view required less pain medication and were able to leave the hospital sooner than patients with a view of a brick wall.
    • Another study found that surgical patients who had plants in their hospital rooms needed less pain medication and had lower blood pressure and heart rates than those without plants.

ForestForest Bathing Reduces Anxiety, Depression, and Stress

Research has also shown that forest bathing is particularly effective for treating negative psychological states such as depression, anxiety, and anger, and that these effects go beyond purely subjective perceptions.

Forest bathing swings the balance toward parasympathetic nervous system activity (rest) as opposed to sympathetic nervous system activity (fight-or-flight). Researchers in Japan have examined the effects of forest bathing in hundreds of people over the years, finding that it causes substantial reductions in the stress hormone cortisol, as well as reduced blood pressure and heart rate, improved mood, and decreased anxiety.

Forest FogFurther support for the beneficial effects of green spaces on mental health comes from studies conducted in various nations:

    • Researchers in Finland found that visiting urban woodlands reduced cortisol levels.
    • A UK meta-analysis found that exercising in green environments improved self-esteem and mood. Mentally ill participants enjoyed the greatest self-esteem improvements.
    • An Australian study found that simply having a view of a plant reduced anxiety, anger, depression, and fatigue by approximately 40% and self-reported stress by 50%. A control group without a plant view suffered an average stress increase of 20% during the study period.
    • Further evidence for the calming effects of nature comes from nationwide U.S. study, which found that spending time in green spaces reduced ADHD symptoms in children.
    • Another recent study found that 90 minutes spent walking in a natural environment reduced the tendency to ruminate (engage in negative thinking), a mental illness risk factor.

Trees on Grouse MountainHow to Forest Bathe

There is no right or wrong way to forest bathe; just spend time in the woods in whatever way feels best for you. However, there are a few things you can do to make the most of your experience:

    • Leave your phone, iPod, and other devices turned off to avoid technological distractions.
    • Look, listen, touch, and smell – experience the forest through multiple senses.
    • Spend as much time as you can. Any time spent green spaces will bring benefits, but longer sessions usually produce the best results.
    • Don’t worry about your mileage. While intense exercise has its own associated health benefits, forest bathing doesn’t require it. Walk at a comfortable pace, and any time you feel like sitting, just relax and enjoy the environment.

ForestIf you’d like more in-depth information about the benefits of forest bathing, all of the studies in the reference list below are available online, either in full or abstract form.

For more health articles, visit the main Mind-Body Health page.

References:

    • Barton, J., & Pretty, J. (2010). What is the best dose of nature and green exercise for improving mental health? A multi-study analysis. Environmental Science & Technology, 44(10), 3947-3955.
    • Bratman, G. N., et al.. (2015). Nature experience reduces rumination and subgenual prefrontal cortex activation. Proceedings of the National Academy of Sciences, 112(28), 8567-8572.
    • Kuo, F. E., & Faber Taylor, A. (2004). A potential natural treatment for attention-deficit/hyperactivity disorder: evidence from a national study. American Journal of Public Health, 94(9), 1580-1586.
    • Li, Q. (2010). Effect of forest bathing trips on human immune function. Environmental Health and Preventive Medicine, 15(1), 9-17.
    • Li, Q., & Kawada, T. Healthy forest parks make healthy people: Forest environments enhance human immune function. Department of Hygiene and Public Health, Nippon Medical School, Tokyo, Japan.
    • Li, Q., et al.. (2009). Effect of phytoncide from trees on human natural killer cell function. International Journal Of Immunopathology and Pharmacology, 22(4), 951-959.
    • Li, Q., et al. (2007). Forest bathing enhances human natural killer activity and expression of anti-cancer proteins. International Journal Of Immunopathology and Pharmacology, 20(2 suppl), 3-8.
    • Maas, J., et al. (2006). Green space, urbanity, and health: how strong is the relation? Journal of Epidemiology and Community Health, 60(7), 587-592.
    • Ohtsuka, Y., et al. (1998). Shinrin-yoku (forest-air bathing and walking) effectively decreases blood glucose levels in diabetic patients. International Journal of Biometeorology, 41(3), 125-127.
    • Park, B. J., et al. (2010). The physiological effects of Shinrin-yoku (taking in the forest atmosphere or forest bathing): evidence from field experiments in 24 forests across Japan. Environmental Health and Preventative Medicine, 15(1), 18-26.
    • Parks Victoria. (2016). Forest Bathing. HPHPCentral.com.
    • Selhub, E., & Logan, A. (2013). Your Brain on Nature: Forest Bathing and Reduced Stress. Mother Earth News, January 8.
    • Tyrväinen, L., et al. (2014). The influence of urban green environments on stress relief measures: A field experiment. Journal of Environmental Psychology, 38, 1-9.
    • Williams, F. (2012). Take two hours of pine forest and call me in the morning. Outside, November 28.