How nature helps fight against chronic stress, poor heart health, and pain

Walking through a forest, with its quiet canopy and cool shadows, offers more than just a break from the hustle-bustle of daily life. There’s growing evidence that spending time in certain environments can alter how the brain processes physical pain.

The science is new, but the observations are not. In Japan, the practice of shinrin-yoku, or forest bathing, encourages people to immerse themselves in nature to soothe both mind and body. And for someone walking through the forest, the physical act of walking itself offers significant health benefits. Now, scientists are beginning to explain why stepping into the green may help relieve stress and certain types of chronic pain.
Research shows that time spent in forests can significantly lower stress hormones like cortisol and reduce symptoms of anxiety and depression. Even a short walk among trees changes how the brain reacts to stress. This “reset” happens quickly, offering almost immediate relief, and has lasting effects even after you leave the forest.
The impact of nature on heart health is especially striking. A review of existing scientific literature on the topic published in the journal Environmental Health and Preventive Medicine in 2020 found that middle-aged and older adults in forest walking programmes experienced notable reductions in blood pressure. Beyond that, spending time in nature boosts heart rate variability, an indicator of a well-functioning cardiovascular system. The evidence suggests that forest therapy could be a valuable addition to the treatment plans to improve heart health.
One of the most intriguing emerging benefits of nature, however, is its potential to alleviate chronic pain. People living with conditions like migraines, fibromyalgia, or arthritis often report feeling better after spending time outdoors, particularly in green spaces.
Scientists are now beginning to understand one of the reasons behind this. A growing body of research shows that the colour green may directly affect how our brains perceive pain.
It turns out that exposure to green wavelengths of light can reduce pain sensitivity in both animals and humans. In one study published in Pain Medicine in 2021, researchers tested green light-emitting diodes on patients with fibromyalgia, a chronic pain disorder that’s difficult to treat. These patients, who had not found relief from standard therapies, were exposed to green light for an hour or more each day over several weeks. Remarkably, they reported a significant reduction in pain intensity, frequency, and duration. They also experienced improvements in sleep quality and overall daily function.
So, how does this work? While the exact mechanisms aren’t fully understood, scientists believe that green light may influence how our brain’s pain pathways operate. Studies have shown that exposure to green light increases the levels of enkephalins, which are natural painkillers produced in the spinal cord. These enkephalins work similarly to opioid drugs but without the risk of addiction or side effects. A green light also appears to reduce inflammation, a key factor in chronic pain.
But the green colour of forests isn’t the only restorative aspect. Forests provide a multi-sensory environment that stimulates the brain in ways that distract from pain. The rustling leaves, the damp smell of soil, and the sound of birds all engage different parts of the brain, pulling attention away from the discomfort of chronic pain.
From an evolutionary perspective, connecting with nature makes sense. Our early ancestors lived in natural environments, relying on the sights, sounds, and smells of their surroundings for survival. The sensory input provided by forests likely shaped how our brains respond to environmental cues, reinforcing a sense of safety and reducing stress levels.
Interestingly, the benefits of nature aren’t limited to long hikes or remote wilderness trips. Even short, frequent exposures to green spaces in urban environments can help. A stroll through a park, sitting under a tree, or spending time in a garden can help lower stress levels and pain perception. This is a realistic, accessible option for people living in cities where green spaces can offer a refuge from the concrete jungle.
Anirban Mahapatra is a scientist and author, most recently of the popular science book, When The Drugs Don’t Work: The Hidden Pandemic That Could End Medicine. The views expressed are personal.