Spending time in nature may be one of the simplest ways to improve health, according to a growing body of scientific research.
Scientists have found that being surrounded by trees, plants and natural landscapes can benefit both the mind and body.
These findings are becoming so convincing that some doctors are now encouraging patients to spend more time outdoors as part of a healthy lifestyle.
The research was highlighted through work involving Harvard Medical School. Susan Abookire, an assistant professor of medicine at Brigham and Women’s Hospital, leads forest therapy sessions for doctors and medical trainees who often experience high levels of stress and burnout. Her work is based on the Japanese practice of shinrin-yoku, commonly known as forest bathing.
Forest bathing does not involve exercise or swimming. Instead, it encourages people to slow down, switch off their phones, notice the sights, sounds and smells around them and become fully present in nature.
Research suggests that even about 20 mindful minutes in nature several times a week can produce measurable health benefits, although longer and more frequent visits appear to provide even greater improvements.
Scientists believe trees play an important role by releasing natural compounds called phytoncides. These tiny airborne substances help protect trees from insects and disease.
Studies from Japan have found that breathing them may increase natural killer cells, which help the immune system fight viruses and some cancers. Some studies suggest these immune benefits may last for weeks after forest visits.
Researchers are also studying plant chemicals called terpenes. These natural compounds are responsible for many familiar plant scents. Laboratory and animal studies suggest certain terpenes may reduce inflammation and could eventually play a role in protecting against diseases such as dementia and cancer, although much more research in humans is still needed.
Nature also appears to improve mental health. Studies show time outdoors activates the parasympathetic nervous system, often called the rest-and-digest system.
This helps calm the body’s fight-or-flight response, reducing stress hormones such as cortisol. Multiple studies have reported lower cortisol levels after forest walks, together with improvements in anxiety, mood and depression.
Sleep may improve as well. Research suggests spending time in forests can increase serotonin activity and improve sleep quality, leaving people feeling more refreshed and focused the next day. Scientists have also reported improvements in blood pressure, heart rate variability and pulse rate after spending time in natural environments.
Researchers believe several factors may work together. Fresh air, birdsong, natural patterns called fractals, pleasant scents from plants and even harmless soil bacteria may all contribute.
Interestingly, studies suggest simply viewing green spaces from a window or looking at natural scenery can improve attention and recovery in hospital patients.
Although many studies support the health benefits of nature, researchers note that more large clinical trials are needed to determine exactly which parts of nature provide the greatest benefits and how much exposure people need.
Much of the current evidence comes from observational studies or relatively small clinical trials.
This research adds to growing evidence that nature is far more than something pleasant to look at. It appears to influence the immune system, brain, heart, sleep and emotional wellbeing in meaningful ways. The study’s strength is that it combines findings from many scientific investigations across different fields.
Its limitation is that many questions remain about cause and effect. Even so, spending time outdoors is inexpensive, accessible for many people and carries very little risk, making it a practical addition to a healthy lifestyle rather than a replacement for medical care.
If you care about mental health, please read studies that vegetarian diet may increase your depression risk, and Vitamin D could help reduce depression symptoms.
For more health information, please see recent studies about why pizza is a very addictive food, and MIND diet could improve cognitive health in older people.
