From Shinrin-Yoku to Forest Therapy – Briefly 

Shinrin-yoku, commonly referred to as “forest bathing,” is a Japanese wellness practice that was first articulated by Tomohide Akiyama, who was the Director-General of the Japanese Forestry Agency. In 1982, under the purview of the Ministry of Agriculture, Forestry, and Fisheries, Akiyama introduced this concept as a natural way of promoting health and well- being as part of the broader 「森林浴構想」) (Forest Bathing Concept). 

The basis of the idea of shinrin-yoku is the belief that staying in the forest and inhaling its unique scent or forest atmosphere, which has a bactericidal effect, improves health and promotes well-being. Akiyama emphasized that forest air, rich in natural essential oils – phytoncides – and other volatile substances, has a beneficial effect on the human body, strengthening physiological and mental health

In 2003, Professor Yoshifumi Miyazaki presented the concept of ‘forest therapy’ (森林 セラピー ), a practice derived from and scientifically augmenting the principles of shinrin- yoku. This approach recognizes the forest as a healing entity and formalizes the therapeutic interaction with nature.Transitioning from the more casual notion of forest bathing, forest therapy involves a more systematic and evidence-based method. Professor Miyazaki’s research underpins the belief in the restorative power of nature, encapsulated in his assertion “The forest heals people” (「森によって人が癒やされる」), highlighting aconviction in the natural world’s capacity to nurture both mental and physical health.

Another noteworthy term is 森林療法 4) (forest treatment), which has been in use since 1999. This term gained prominence during the 115th Congress of the Japanese Forestry Association (日本林学会 ) held at Ehime University, where a presentation titled “The desire to develop forest therapy” (「森林療法の構築を目指して」) was delivered. This presentation marked one of the first formal introductions of the forest therapy concept. In 2002, the momentum continued with the establishment of the Forest Therapy Research Group in Karuizawa, Nagano Prefecture. Comprising local citizens, this group embarked on initiatives to leverage the region’s forests for health and well-being. Subsequently, in 2003, the Japanese Forestry Agency (林野庁 ) released a comprehensive report on forest utilization. The report highlighted forest therapy as a strategy for enhancing health through the multifaceted use of forest environments, underscoring the therapeutic value of forests in public health promotion.

In March 2004, a pivotal step was taken with the formation of a forest therapy research group, which included observers from the Japan Forest Agency and the Ministry of Health, Labor and Welfare. This group was tasked with fostering the utilization of forests for health and recreational purposes, emphasizing a collaborative effort between public and private sectors alongside academic institutions. Simultaneously, as the “Basic Law on Forests and Forestry” (「森林・林業基本法」) was introduced, local governments began to show a heightened interest in forest therapy. This was in line with a broader initiative to harness the diverse functions of forests. The burgeoning interest has since spurred the creation and expansion of various forest therapy programs across Japan, contributing significantly to the nationwide establishment and popularity of shinrin-yoku paths.

Drawing from the foundation laid by years of study, what began as shinrin-yoku and has evolved into forest therapy is now acknowledged not merely as a method for relaxation but as a vital component in supporting human health and well-being. This practice has garnered global recognition as a means to alleviate stress, enhance mood, and bolster overall health, underscoring its significance in contemporary wellness approaches.

The Continuum

Scientific research offers numerous insights into how we can effectively manage stress and promote a state of calm. Our bodies possess inherent mechanisms that both trigger stress responses and inhibit them, fostering calmness when necessary. This process is rooted in the biological interplay between stress and calm.

At the core of this regulation is the nervous system, a sophisticated network that facilitates bidirectional communication between the brain and the body. The nervous system is composed of the central nervous system (CNS), which includes the brain and spinal cord, and the peripheral nervous system (PNS), which connects the CNS to the rest of the body.

The nervous system operates by converting external stimuli (such as smell, touch, and sound) into electrical signals and neurochemical transmissions that can be interpreted and processed by the brain. This sensory information allows the brain to generate perceptions, emotions, thoughts, and behaviors. In addition to processing external inputs, the nervous system also manages critical autonomic functions, such as heart rate, respiration, and digestion, which are necessary for survival and do not require conscious thought.

Crucially, the nervous system regulates autonomic arousal—the physiological state that determines our level of alertness or calmness. Arousal states are mediated by the autonomic nervous system (ANS), which consists of two branches: the sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS). The SNS activates the body’s “fight or flight” response during stressful situations, increasing arousal levels, while the PNS promotes “rest and digest” functions, reducing arousal and fostering calm.

This regulation of arousal is fundamental to human functioning, as it influences sensory processing, cognitive performance, emotional responses, and behavioral outputs. The state of autonomic arousal dictates what we perceive, how we think, and how we act in response to external and internal stimuli. Understanding the biological underpinnings of stress and calm allows for more effective strategies in managing these states and optimizing mental and physical well-being.

The below image shows the Autonomic/Arousal Continuum 

 ALERT Sub-continuum　　CALM Sub-continuum

The Arousal Continuum depicted in the image reflects the range of arousal states our nervous system can experience, moving from very high arousal (panic) to very low arousal (coma). This continuum can be explained using principles of neuroscience, particularly how the autonomic nervous system (ANS) regulates our body’s response to stress, relaxation, and alertness. The ANS is divided into two primary branches:

1. Sympathetic Nervous System (SNS): This system is responsible for the “fight or flight” response, activating during high arousal states such as stress, alertness, and panic. It prepares the body to deal with perceived threats by increasing heart rate, dilating pupils, increasing blood flow to muscles, and releasing stress hormones like adrenaline. The red side of the continuum (panic, stressed, highly alert) is driven primarily by sympathetic activation.

2. Parasympathetic Nervous System (PNS): In contrast, the parasympathetic system controls the “rest and digest” responses, promoting relaxation, recovery, and conservation of energy. This is associated with states of calmness, drowsiness, deep sleep, and coma on the green side of the continuum. When the PNS is activated, heart rate decreases, digestion is promoted, and the body relaxes.

Breakdown of the Continuum:

• Panic (Far left, high arousal): At the extreme end of sympathetic activation, panic reflects a state of intense fear or danger, flooding the body with stress hormones. This is an emergency response where cognitive control can be diminished, and survival instincts take over.

• Very Stressed and Stressed: These are high-arousal states where the sympathetic system is still in charge, but not to the extreme of panic. Chronic stress over time can keep the body in a sustained state of sympathetic activation, leading to health problems like high blood pressure and anxiety disorders.

• Highly Alert: This is a state where you are aware and ready to act, but not overwhelmed. It’s a level of arousal that enhances cognitive performance, focus, and reaction time, driven by the SNS but in a controlled way.

• Alert & Calm (Midpoint): This is the ideal balance between sympathetic and parasympathetic activation. In this state, you are aware and capable of taking action, but not stressed or agitated. Your body is not preparing for a threat, but you remain fully conscious and engaged.

• Alert, Drowsy, Deep Sleep, Coma (Far right, low arousal): These are progressively deeper parasympathetic states. As we move from alert to drowsy, the brain and body start winding down, reducing heart rate, blood pressure, and other physiological activities. Deep sleep involves full parasympathetic dominance, crucial for restoration and healing. A coma represents the lowest level of arousal, where conscious brain activity is almost non-existent.

The Connection to Shinrin Yoku: Scientific Pathway 

Forest phytoncides, the volatile organic compounds emitted by trees and plants, have been shown to significantly influence the arousal continuum by promoting physiological and psychological states of calm. These compounds, which include substances like α-pinene, limonene, and β-pinene, are released by trees as part of their defense mechanism against insects, bacteria, and fungi. For humans, exposure to phytoncides has an impact on the nervous system, particularly in how it interacts with the autonomic arousal continuum.

Effects of Phytoncides on the Autonomic Nervous System

Phytoncides primarily act by influencing the balance between the sympathetic nervous system (SNS), responsible for the body’s stress and alert responses, and the parasympathetic nervous system (PNS), which promotes relaxation and recovery.

1. Reduction in Sympathetic Activity: Research shows that exposure to phytoncides lowers levels of cortisol, a stress hormone, and reduces sympathetic arousal. When cortisol and other stress markers decrease, the body transitions from heightened states of arousal, such as “stressed” or “highly alert,” to more balanced states like “alert & calm” or even toward relaxation. This shift helps move individuals away from the left side of the arousal continuum (high stress, panic) toward the center, promoting mental clarity without overstimulation.

2. Increase in Parasympathetic Activity: Simultaneously, phytoncides enhance parasympathetic nervous system activity, which induces calm and supports recovery processes. Studies have shown increases in heart rate variability (HRV)—a marker of parasympathetic activation—after spending time in forest environments rich in phytoncides. The heightened PNS activity facilitates states of deep relaxation, which are located on the right side of the arousal continuum, such as “drowsy” or “deep sleep.”

Influence on Cognitive and Emotional States

By modulating the balance between sympathetic and parasympathetic activity, forest phytoncides affect cognitive functioning, mood, and emotional regulation:

• Enhanced Relaxation and Lower Anxiety: The calming effects of phytoncides help reduce anxiety and promote a sense of peace. This helps individuals transition from states of hyper-arousal (stress, panic) to a more balanced, relaxed state.

• Improved Cognitive Clarity: While phytoncides reduce over-activation of the SNS, they do not impair alertness. Individuals report improved cognitive clarity and focus when moving toward the middle of the arousal continuum (“alert & calm”). This allows for better mental performance without the detrimental effects of stress.

• Mood Stabilization: Forest exposure has been associated with increased levels of serotonin, a neurotransmitter linked to mood regulation, which further enhances emotional stability and decreases irritability and fatigue.

The Connection to Shinrin Yoku: Spiritual Pathway

The sense of calm induced by the practice is connected to both physiological and psychological transformations within the nervous system. As the parasympathetic nervous system becomes more dominant, the body shifts into a state of relaxation. While the shift not only reduces physical stress markers, such as cortisol, what does create space for? Perhaps greater mental clarity and introspection?

When your nervous system enters this state of calm, a few key processes may unfold:

1. Reduction in External Noise Perception: As you relax, the brain’s focus shifts away from external stressors or distractions. This is similar to how noise-canceling headphones block out disruptive sounds. In a calm state, sensory overload diminishes, and the mind becomes more attuned to subtle aspects of your environment or inner world. In this quiet space, there is less interference from the noise of daily life, and your perception sharpens.

2. Heightened Presence: With the sympathetic (fight-or-flight) system no longer dominating, you become more present. This presence means a deeper connection to the current moment—heightening awareness of the sights, smells, and sensations of the forest. By quieting internal and external noise, you’re able to perceive the world with fresh eyes, leading to a sense of renewal.

3. Shifting Perspectives: In this calm, you can reflect on your life, your emotions, and your goals with greater objectivity. In moments of clarity and calm, you can more easily access your intuitive sense and your creativity.  Shinrin Yoku often allows for shifts in perspective because, in a state of calm, you are no longer reacting to stress. Instead, you may be able to  access deeper layers of thought and emotion, fostering insight, gratitude, and even solutions to long-standing problems.

On a spiritual level, Shinrin Yoku can facilitate moments where the boundary between the self and nature dissolves, creating a feeling of interconnectedness. This spiritual experience deepens the sense of calm and, in turn, opens new pathways. When we are no longer distracted by the mental noise of daily life, our capacity to see things in a new light expands. 

It may be that Shinrin Yoku doesn’t merely reduce stress—it acts as a catalyst for personal transformation.  

At the The Mindful Tourist: 森の心・人の心 (The Teart of the Forest ・The Heart of Human) we strongly believe that it actually does take us through the journey of reaching our hearts to support our healing.