10-2Forest therapy and preventive medical effect / 日本温泉気候物理医学会雑誌

ABSTRACT

  The human species have existed for 6-7 million years. Because over 99.99% of our evolutionary history has been spent in natural environments, it is considered that we are adaptive to nature¹⁾. However, we now live in a society that is characterized by urbanization and artificiality, despite our physiological functions still being adapted to nature. <BR>  We conducted experiments involving 420 subjects at 35 different forests throughout Japan²⁾. Participants in natural surroundings showed the following physiological decreases compared with those in an urban control group: 12.4% decrease in cortisol level, 7.0% decrease in sympathetic nervous activity, 1.4% decrease in systolic blood pressure, and 5.8% decrease in heart rate. This suggests that stressful states can be relieved by forest therapy. In addition, parasympathetic nervous activity was enhanced by 55.0%, indicating a relaxed state. The results of similar experiments that involved walking in forests were equivalent. Li et al. demonstrated that immune function was enhanced by forest therapy in middle-aged employees who volunteered to participate in these experiments. Natural killer cell activity, an indicator of immune function, was enhanced by 56% on the second day and returned to normal levels. A significant increase of 23% was maintained for 1 month even after returning to urban life, clearly illustrating the preventive benefits of forest therapy³⁾. <BR>  In conclusion, forest therapy had preventive benefits and facilitated physiological relaxation and immune recovery⁴⁾ (Figure 1).