池井 晴美

There is a significant positive relationship between exposure to forest environments and physical and mental health. However, there are individual differences within these responses, and this phenomenon has posed questions in various fields. Here, we show that the physiological effect of a forest environment can differ depending on a subject’s initial values and that forests have a physiological adjustment effect close to an appropriate level. Subjects with high initial blood pressure and pulse rate showed a decrease in these values after walking in a forested area, whereas those with low initial values showed an increase. There was no physiological adjustment effect observed in an urban area thus, these effects are specific to a forest environment.

There has been increasing attention on the therapeutic effects of the forest environment. However, evidence-based research that clarifies the physiological effects of the forest environment on hypertensive individuals is lacking. This study provides scientific evidence suggesting that a brief forest walk affects autonomic nervous system activity in middle-aged hypertensive individuals. Twenty participants (58.0 ± 10.6 years) were instructed to walk predetermined courses in forest and urban environments (as control). Course length (17-min walk), walking speed, and energy expenditure were equal between the forest and urban environments to clarify the effects of each environment. Heart rate variability (HRV) and heart rate were used to quantify physiological responses. The modified semantic differential method and Profile of Mood States were used to determine psychological responses. The natural logarithm of the high-frequency component of HRV was significantly higher and heart rate was significantly lower when participants walked in the forest than when they walked in the urban environment. The questionnaire results indicated that, compared with the urban environment, walking in the forest increased “comfortable”, “relaxed”, “natural” and “vigorous” feelings and decreased “tension-anxiety,” “depression,” “anxiety-hostility,” “fatigue” and “confusion”. A brief walk in the forest elicited physiological and psychological relaxation effects on middle-aged hypertensive individuals.

The relaxation effects of gardening have attracted attention however, very few studies have researched its physiological effects on humans. This study aimed to clarify the physiological and psychological effects on high school students of viewing real and artificial pansies. Forty high school students (male: 19, female: 21) at Chiba Prefectural Kashiwanoha Senior High School, Japan, participated in this experiment. The subjects were presented with a visual stimulation of fresh yellow pansies (Viola x wittrockiana “Nature Clear Lemon”) in a planter for 3 min. Artificial yellow pansies in a planter were used as the control. Heart rate variability was used as a physiological measurement and the modified semantic differential method was used for subjective evaluation. Compared with artificial pansies, visual stimulation with real flowers resulted in a significant decrease in the ratio of low- to high-frequency heart rate variability component, which reflects sympathetic nerve activity. In contrast, high frequency, which reflects parasympathetic nerve activity, showed no significant difference. With regard to the psychological indices, viewing real flowers resulted in “comfortable”, “relaxed”, and “natural” feelings. The findings indicate that visual stimulation with real pansies induced physiological and psychological relaxation effects in high school students.

Time spent walking and relaxing in a forest environment (“forest bathing” or “forest therapy”) has well demonstrated anti-stress effects in healthy adults, but benefits for ill or at-risk populations have not been reported. The present study assessed the physiological and psychological effects of forest therapy (relaxation and stress management activity in the forest) on middle-aged males with high-normal blood pressure. Blood pressure and several physiological and psychological indices of stress were measured the day before and approximately 2 h following forest therapy. Both pre- and post-treatment measures were conducted at the same time of day to avoid circadian influences. Systolic and diastolic blood pressure (BP), urinary adrenaline, and serum cortisol were all significantly lower than baseline following forest therapy (p &lt 0.05). Subjects reported feeling significantly more “relaxed” and “natural” according to the Semantic Differential (SD) method. Profile of Mood State (POMS) negative mood subscale scores for “tension-anxiety,” “confusion,” and “anger-hostility,” as well as the Total Mood Disturbance (TMD) score were significantly lower following forest therapy. These results highlight that forest is a promising treatment strategy to reduce blood pressure into the optimal range and possibly prevent progression to clinical hypertension in middle-aged males with high-normal blood pressure.

Several million years have passed since a subset of primates became humans. Because we spent more than 99.99% of our evolutionary history in natural environment, it is considered that we are essentially adaptive to nature. However, we live in a society characterized by urbanization and artificiality despite our physiological functions still being adapted to a natural environment. According to the concept of evidence-based medicine, we reviewed preventive medical effects of nature therapy, which comprised forest, park, wood, and flower therapy. We collected scientific data from field and laboratory experiments using physiological indicators. We expect nature therapy to play an increasingly important role in preventive medicine in the future.

BACKGROUND AND PURPOSE Natural scenes like forests and flowers evoke neurophysiological responses that can suppress anxiety and relieve stress. We examined whether images of natural objects can elicit neural responses similar to those evoked by real objects by comparing the activation of the prefrontal cortex during presentation of real foliage plants with a projected image of the same foliage plants. METHODS Oxy-hemoglobin concentrations in the prefrontal cortex were measured using time-resolved near-infrared spectroscopy while the subjects viewed the real plants or a projected image of the same plants. RESULTS Compared with a projected image of foliage plants, viewing the actual foliage plants significantly increased oxy-hemoglobin concentrations in the prefrontal cortex. However, using the modified semantic differential method, subjective emotional response ratings ("comfortable vs. uncomfortable" and "relaxed vs. awakening") were similar for both stimuli. CONCLUSIONS The frontal cortex responded differently to presentation of actual plants compared with images of these plants even when the subjective emotional response was similar. These results may help explain the physical and mental health benefits of urban, domestic, and workplace foliage.

Objectives: To examine the psychological effects of forest therapy program on workers. Methods: The subjective symptoms index, a shortened version of the profile of mood states (POMS), and a semantic differential (SD) method were used to measure the psychological effects. Results: The evaluations were performed 3 days before, during, and 1, 3, and 5 days after the forest therapy. The following results were obtained: (1) the subjective symptoms improved before breakfast and continued for 5 days; (2) the mood evaluated using POMS improved before breakfast and continued for 3 days; and (3) "comfortable," "relaxed," and "natural" feelings evaluated using the SD method were enhanced before breakfast, lunch, and dinner during forest therapy. Conclusions: These results provided scientific evidence of the psychological effects of forest therapy program on workers.

Autonomic responses to urban and forest environments were studied in 625 young male subjects. The experimental sites were 57 forests and 57 urban areas across Japan. The subjects viewed the landscape (forest or urban environment) for a period of 15 min while sitting on a chair. During this period, heart rate variability (HRV) was monitored continuously. The results were presented as histograms and analyzed with special reference to individual variations. Approximately 80% of the subjects showed an increase in the parasympathetic indicator of HRV (lnHF), whereas the remaining subjects showed a decrease in the parasympathetic activity. Similarly, 64.0% of the subjects exhibited decreases in the sympathetic indicator of HRV (ln[LF/HF]), whereas the remaining subjects showed opposite responses. Analysis of the distribution of HRV indices (lnHF and ln[LF/HF]) demonstrated the effect of forest environments on autonomic activity more specifically than the conventional analysis based on the difference in mean values.

Objectives: People have been aware of essential oils, which are derived from plants, for a long time. Recently, we have become interested in physiological and subjective effects of daily exposure to essential oils. The primary aim of the present study was to clarify effects of olfactory stimulation with rose or orange oil on prefrontal cortex activity; subjective evaluations of relaxation were also determined. Setting and interventions: Subjects were exposed for 90s to air impregnated with either rose or orange essential oil. As a control, subjects wore the same device but inhaled only unimpregnated air. The three stimuli were randomly presented to each subject. Main outcome measures: Physiological effects were determined by near-infrared time-resolved spectroscopy and a modified semantic differential approach was used to determine subjective evaluations. Results: The study participants were 20 female university students (mean age 22.5 +/- 1.6 years). Olfactory stimulation by rose or orange oil induced: (1) a significant decrease in oxyhemoglobin concentration in the right prefrontal cortex and (2) an increase in "comfortable," "relaxed," and "natural" feelings. Conclusion: These findings indicate that olfactory stimulation by rose or orange oil induces physiological and psychological relaxation. (C) 2014 Elsevier Ltd. All rights reserved.

Empirical evidence suggests that three-dimensional (3D) images of nature promote physiological relaxation in humans by providing more realistic effects compared with two-dimensional (2D) images. However, no studies have evaluated the physiological relaxation effects of nature-derived 3D images on prefrontal cortex and autonomic nerve activity. The present study aimed to clarify the physiological relaxation effects of visual stimulation by 3D flower images on prefrontal cortex and autonomic nerve activity. Nineteen male university students (22.2 +/- 0.6 years) were presented with 3D and 2D images of the water lily for 90 s. Prefrontal cortex activity was measured using near-infrared spectroscopy, while autonomic nerve activity was measured using heart rate variability (HRV). Psychological effects were determined using a modified semantic differential method (SD). Compared with visual stimulation by 2D images, that by 3D images resulted in a significant decrease in oxyhemoglobin concentration in the right prefrontal cortex, lower sympathetic activity as calculated by the ratio of the low-frequency to high-frequency HRV component, and a significantly greater realistic feeling as evidenced by higher SD ratings. In conclusion, visual stimulation by realistic 3D floral images promotes physiological relaxation more effectively than the corresponding 2D image.

Objective: To clarify the effect of olfactory stimulation by fresh rose flowers, which exude a strong fragrance, on heart rate variability. Settings: A chamber with an artificial climate maintained at 25 degrees C with 50% relative humidity and 230 lux illumination at the Center for Environment, Health, and Field Sciences, Chiba University, Japan. Participants: Nineteen female university and graduate students (mean age, 21.6 +/- 1.5 years; age range, 19.0-26.0 years). Interventions: Fresh rose flowers as an olfactory stimulant, with air as a control. Outcome measures: Heart rate variability and subjective evaluations. The power levels of the high-frequency (HF) (0.15-0.40 Hz) and low-frequency (LF) (0.04-0.15 Hz) components of heart rate variability were calculated by the maximum-entropy method. The HF power was considered to reflect parasympathetic nervous activity. The LF/HF power ratio was determined to reflect the sympathetic nervous activity. A modified semantic differential method was used to perform subjective evaluations. Results: Fresh rose flowers induced (1) a significant increase in parasympathetic nervous activities and (2) an increase in "comfortable'' and "natural'' feelings. Conclusion: The findings indicated that olfactory stimulation by fresh rose flowers induced physiological and psychological relaxation.

Objectives: To clarify the effect of olfactory stimulation with perilla essential oil on human prefrontal cortex activity using near-infrared time-resolved spectroscopy. Design: Single-center prospective study. Methods: Nineteen female university students (mean age, 21.6 +/- 1.5 years) participated in the study. Perilla essential oil was used as an olfactory stimulant and air as a control. Oxyhemoglobin concentrations in the prefrontal cortex were measured by using near-infrared time-resolved spectroscopy when the participants were presented with the stimulant or control. Emotional effects were subjectively evaluated by using a modified semantic differential method. Results: Olfactory stimulation with the perilla essential oil significantly reduced the oxyhemoglobin concentration in the prefrontal cortex. No significant differences in the feelings of comfort or relaxation, which strongly reflect human mental status, were observed between the perilla essential oil and control periods. Conclusions: Olfactory stimulation with perilla essential oil reduced prefrontal cortex activity, thereby inducing physiologic relaxation.

The interests in promotion of health and well-being through gardening activities are high. This article reviewed the psychological and psychological effects of gardening activities from domestic and foreign precedent studies. Although mental and physical health improvements due to gardening activities were reported, this review shows that most measurements are based on a subjective estimation or an interview. There were extremely few accumulations of data based on scientific evidence. Therefore, the importance of physiological evaluation made from a future preventive medical viewpoint was highlighted.

Background: It is widely believed that contact with the natural environment can improve physical and mental health. Urban green spaces may provide city residents with these benefits however, there is a lack of empirical field research on the health benefits of urban parks. Methods: This field experiment was performed in May. Seventeen males aged 21.2 ± 1.7 years (mean ± standard deviation) were instructed to walk predetermined 15-minute courses in an urban park and a nearby city area (control). Heart rate and heart rate variability (HRV) were measured to assess physiological responses. The semantic differential (SD) method, Profile of Mood States (POMS), and State-Trait Anxiety Inventory (STAI) were used to measure psychological responses. Results: Heart rate was significantly lower while walking in the urban park than while walking in the city street. Furthermore, the urban park walk led to higher parasympathetic nervous activity and lower sympathetic nervous activity compared with the walk through the city street. Subjective evaluations were generally in accordance with physiological reactions, and significantly higher scores were observed for the 'comfortable', 'natural', and 'relaxed' parameters following the urban park walk. After the urban park walk, the score for the 'vigor' subscale of the POMS was significantly higher, whereas that for negative feelings such as 'tension-anxiety' and 'fatigue' was significantly lower. The score for the anxiety dimension of the STAI was also significantly lower after the urban park walk. Conclusions: Physiological and psychological results from this field experiment provide evidence for the physiological and psychological benefits of urban green spaces. A brief spring-time walk in an urban park shifted sympathetic/parasympathetic balance and improved mood state. © 2014 Song et al. licensee BioMed Central Ltd.

Background: In recent years, the physiological relaxing effect brought by nature is becoming clear; however, many workers find it difficult to be exposed to nature in their working environment. Exposure to fresh flowers represents an opportunity to incorporate nature into their working lives. In this study, we examined the effects of exposure to roses on physiological and psychological variables (heart rate variability, pulse rate, and subjective responses) in office workers. Results: The experimental site was Mizuho Information & Research Institute, Inc., in the Tokyo metropolitan area. Thirty-one male office workers were included in the present study. The subjects were exposed to thirty unscented pink roses (Rosa, Dekora) arranged in a cylindrical glass vase for 4 min. In the control condition, the subjects were not exposed to flowers. After the experiments, the subjects completed a questionnaire. The order of exposure was counterbalanced among subjects. Among subjects exposed to roses, the high-frequency component of heart rate variability was significantly higher than in controls. Similarly, `comfortable,' `relaxed' and `natural' feelings were more common in subjects exposed to roses. Conclusions: Data from this study support the presence of physiological and psychological relaxing effects of being exposed to flowers on office workers.

Background. Despite increasing attention toward forest therapy as an alternative medicine, very little evidence continues to be available on its therapeutic effects. Therefore, this study was focused on elucidating the health benefits of forest walking on cardiovascular reactivity. Methods. Within-group comparisons were used to examine the cardiovascular responses to walking in forest and urban environments. Forty-eight young adult males participated in the two-day field research. Changes in heart rate variability, heart rate, and blood pressure were measured to understand cardiovascular reactivity. Four different questionnaires were used to investigate the changes in psychological states after walking activities. Results. Forest walking significantly increased the values of ln(HF) and significantly decreased the values of ln(LF/HF) compared with the urban walking. Heart rate during forest walking was significantly lower than that in the control. Questionnaire results showed that negative mood states and anxiety levels decreased significantly by forest walking compared with urban walking. Conclusion. Walking in the forest environment may promote cardiovascular relaxation by facilitating the parasympathetic nervous system and by suppressing the sympathetic nervous system. In addition, forest therapy may be effective for reducing negative psychological symptoms.

Rapid urbanization and artificialization have caused environmental changes that threaten human health and quality of life. However, there is a lack of evidence-based research focused on the physiological and psychological impacts of urban environments. The aim of this study was to clarify the physiological and psychological impacts of urban environments using a field experiment. Thirty-six Japanese male university students (mean age 22.1 ± 1.8 years) participated in the study, each was instructed to walk a predetermined 13-min course in an urban area (test) and forested area (control). Heart rate and heart rate variability were measured to assess physiological responses to the environment. The semantic differential method for assessing emotions and reports of feeling “refreshed” were used to determine psychological responses. Heart rate was significantly higher and the high-frequency component of heart rate variability, which is an index of parasympathetic nervous activity that is enhanced in relaxing situations, was significantly lower when the subjects walked through urban than through forested areas. Moreover, the psychological indices showed that the subjects felt more artificial and less “refreshed” when walking in the urban areas. In conclusion, these findings provide important scientific evidence of physiological and psychological impacts of walking stress in urban environments.

Background: Interaction with nature has a relaxing effect on humans. Increasing attention has been focused on the therapeutic effects of urban green space however, there is a lack of evidence-based field research. This study provided scientific evidence supporting the physiological and psychological effects of walking on young males in urban parks in winter.Findings: Subjects (13 males aged 22.5 ± 3.1 years) were instructed to walk predetermined 15-minute courses in an urban park (test) and in the city area (control). Heart rate and heart rate variability (HRV) were measured to assess physiological responses. The semantic differential (SD) method, Profile of Mood States (POMS), and State-Trait Anxiety Inventory (STAI) were used to determine psychological responses. Heart rate was significantly lower and the natural logarithm of the high frequency component of HRV was significantly higher when walking through the urban park than through the city area. The results of three questionnaires indicated that walking in the urban park improved mood and decreased negative feelings and anxiety.Conclusions: Physiological and psychological data from this field experiment provide important scientific evidence regarding the health benefits of walking in an urban park. The results support the premise that walking in an urban park has relaxing effects even in winter. © 2013 Song et al. licensee BioMed Central Ltd.

Background: In recent years, the physiological relaxation effects of natural environments have been widely exploited, and although individual differences in the effects of forest therapy are known, assessment methods have not been clearly established. This study used a classification based on Type A and Type B behavior patterns to explain individual differences in physiological responses to forest environments. Methods: We performed physiological experiments in 44 forest and urban (controls) areas. In total, 485 male university students (age, 21.8 ± 1.6 years) participated in the study. The subjects were asked to visit forest or urban environments randomly and observe each landscape for 15 min. The subjects' pulse rates and blood pressures were tested to evaluate their physiological responses. The Kwansei Gakuin daily life questionnaire was used to identify Type A and Type B behavior patterns in subjects. Results: The pulse rate was significantly lower in the Type B group after exposure to forest areas than after exposure to urban areas, whereas no significant difference was observed in the Type A group. In addition, the pulse rate was significantly lower in the low scoring subjects in the Type B group, which was consistent with changes in their diastolic blood pressure. Conclusions: These results suggest that individual differences in pulse rate and blood pressure in response to forest environments can be explained by Type A and Type B behavior patterns. © 2013 Song et al. licensee BioMed Central Ltd.

This study aims at clarifying the physiological relaxing effect which pink rose brings about for 55 high school students. The stimulation was made by 30 pink roses with non-scent arranged in a vase while the control had no flower for 4 minutes. The physiological indices were the heart rate variability and pulse rate which employed fingertip accelerated plethysmography, and the psychological indicators were the SD method and the shortened version of profile of mood states (POMS). The results as follow: (1) HF were significantly higher, and LF/HF were significantly lower, (2) "comfortable", "natural", and "relaxed" feelings and the mood state were significantly better, while viewing fresh rose flowers than control.

The physiological effects of viewing rose flowers on medical staff were examined to investigate heart rate variability, the pulse rate, and questionnaire responses. Subjects were 15 female medical staff, who looked at fresh rose flowers for 4 minutes. Thirty unscented pink roses (Rosa, Dekora) were arranged in a cylindrical glass vase, and the control was no roses. Physiological measurements were recorded during visual stimuli and control (no flowers) presentation. The results were as follows: (1) the HF component was significantly higher, and pulse rate was significantly lower, (2) "comfortable", and "relaxed" feelings and the mood state were significantly better, and state anxiety was significantly lower while viewing fresh rose flowers compared to the control.