As we've reported, there is no questioning the fact that stepping outside for fresh air brings fresh perspective and that taking a stroll on the beach causes a sense of serenity. Why? What is it about nature that produces a calming effect and a feeling of being grounded?

Scientists have been searching for the answers to these questions for years and a multitude of studies have been conducted in an attempt to uncover a scientific explanation.

Stanford University scientists believed that being surrounded by nature reduces pessimistic rumination by providing a pleasant distraction from being lost in whirling negative thoughts. Their study, published in the Proceedings of the National Academy of Sciences, looked at how nature walks can diminish self-referential negative thinking, a behavior associated with mental illnesses, such as depression.

The participants who went on a nature walk reportedly had less activity in their subgenual prefrontal cortices, the area of the brain that controls negative feelings, and the half who walked down an urban four-lane road had no improvement in brain activity. Like any other positive distraction, being outside redirects sullen thinking, however when compared to other positive distractions, being in nature had the greatest effect on the brain.

Other scientists looked at the amounts of cortisol, the stress hormone, in people when surrounded by the natural environment. Those living in wide, open green spaces have lower cortisol levels than those living in urban environments, according to a study published in Landscape and Urban Planning. This is partly due to the fact that the natural world motivates light exercise, which is the best natural mood-booster as it produces endorphins, the feel-good hormone, according to the study.

A 2014 Japanese study found that when subjects were placed in forests they not only had a reduction in cortisol levels, but also decreases in blood pressure, heart rate, and the "fight or flight" response. Parasympathetic nervous activity, or the part of the nervous system that makes people relax, increased by 55 percent in study participants and immunity rose 56 percent.

University of Illinois Environment and Behavior researcher Ming Kuo analyzed hundreds of studies regarding the natural environment and health and believes that the reason people achieve relaxation outdoors is because the natural environment strengthens our immune system. Kuo claims that being outside bolsters immunity by shifting us from "fight or flight" mode, an imitation of stress, to "rest and digest" mode, allowing our body to restore itself and thus improve all areas of human health.

Even the visual imagery of a natural scene enhances mental and physical health. A 1984 study published in Science showed that those recovering from surgery with a window view of a forest healed faster and were in less distress than those recovering in a room without a view.

These scientific studies prove that humans need the natural world to survive; our bodies are attuned with nature. Isolation, excessive indoor activity, and high-stress urban living situations are all negatively influencing the human bodies' immune, nervous, and endocrine systems. While that catnap may make you feel better for a short while, a short walk in the woods is the absolute best way to lower stress. It's scientifically proven.

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