Forest-bathing or forest therapy walks are conducive to increasing the function of the parasympathetic nervous system, which is responsible for keeping us calm. When we feel stressed, we are under the control of the sympathetic nervous system that secretes cortisol and other stress hormones to prepare us for a fight-or-flight response. We need these stress hormones to respond to emergency situations, but we don't need this level of stress every day. However, many people exhibit symptoms of high levels of stress and elevated stress hormone levels regularly, which can lead to chronic anxiety and depression disorders, headaches, anger issues, high blood pressure, cardiac disease, alcohol and/or drug abuse, weight gain, and impaired cognitive function. Scientific studies report reductions of salivary cortisol by 12 to 13 percent following a leisurely forest walk. And, these reduced levels remain even after the walk. The length of reduction time correlates with the amount of time spent in the forest. A longer walk translates into a longer period of reduced stress hormones.
Increases Immune System Function
Forest therapy walks also result in increased immunity. Stress can impair our immune function, making us easier prey for viruses, bacteria, and even cancer. When we are under constant stress, the hormones circulating in our bodies decrease the number of our natural killer cells, which seek out and destroy invaders. If those viruses, bacteria, and cancerous cells are allowed to stick around, they can cause illnesses that we would all prefer to avoid. In a scientific study in 2007, men who took two-hour walks in forests on two consecutive days were found to have a 50 percent increase in their natural killer cells. In another study in 2008, Dr. Qing Li studied 13 female nurses on a three-day forest-bathing trip and found the trip produced anti-cancer proteins and benefits lasting more than seven days after the trip. Studies are ongoing by Dr. Li and others in the scientific community.
Enhances Mental Processes
Spending time immersed in nature pushes the reset button on our brains, allowing us to come back to our everyday tasks with renewed energy, focus, and creativity. The forest also offers benefits for people — adults and children — with attention disorders. A study conducted by David Strayer found that Outward Bound wilderness backpackers performed 50 percent better on creative problem-solving tasks after returning from a three-day trip. As he conducts further research, he suggests that time spent in nature "allows the prefrontal cortex, the brain's command center, to dial down and rest, like an overused muscle." With the distractions of modern life, our brains can use the break. During a forest therapy walk, participants are guided in a deep sensory exploration of a forest trail. During the slowly paced walk, there's time to notice the beauty along the trail.
Exposes us to Fresh Air and Phytoncides
When we enter the forest, one of the first things most of us feel led to do is to take a deep breath. And, while we've always known that fresh air is good for us, now we have some idea about the reason. Trees and plants release organic substances into the air called phytoncides. Scientists have identified these phytoncides, especially from conifers, as beneficial in helping us relax and in boosting our immunity. While there is still much to learn about phytoncides, we know that earlier generations spent much more time in nature than many of us do today, so the human body, at one time, was acclimated to the outdoors and the phytoncides present in the air. I wonder if our recent move as a species from a primarily outdoor lifestyle to a primarily indoor lifestyles could cause us to experience problems caused by a deficit in these beneficial organic substances. Scientists are already discovering the many benefits phytoncides offer us.