Elucidation of a physiological adjustment effect in a forest environment: a pilot study

The effect of forest-based health and wellness on the stress-relieve of middle-aged people

In order to explore the impact of experience in forest-based health and wellness (FHW) on the stress of middle-aged people, 12 participants aged 35-39 were selected to conduct a 3-day/2-night study on FHW experience in Wencheng, Wenzhou. Huawei bracelets were used to monitor participants' movement, pulse and blood pressure and their mood state was measured before and after the health care experience using the Profile of Mood States (POMS) scale. After the FHW experience, the lowest value of bracelet stress appeared on the second day of the experience for men and women. The total mood disturbance (TMD) decreased by 38.8 points on average, which significantly improved the positive mood and relieved the stress. The decompression effect of the FHW experience showed some variability among individuals. Furthermore, there were gender differences in alleviation of fatigue and puzzlement, which was greater for females than males.

Exploring the effect of different typical plant community on human stress reduction: a field experiment

Research has demonstrated the positive effect of natural environment on human restoration and well-being. Time spent in nature can often alleviate both physiological and psychological stress. However, few studies have discussed the environmental health effects of the nature's components and characteristics. Sixty volunteers were recruited and one manufactured environment and five different natural environments were randomly assigned to them, including coniferous forests (pure coniferous forest-PC and mixed coniferous forest-MC), broad-leaved forests (pure broad-leaved forest-PB and mixed broad-leaved forest-MB), and mixed forest (mixed coniferous and broad-leaved forest-MCB). Each volunteer sat in a built or natural environment and looked around the environment for 15 min. Physiological (HR, HRV, BP, pulse rate and salivary cortisol) and psychological indicators (POMS and STAI) were used to evaluate the changes in their stress level. Results indicated a strong difference in HR, HRV, POMS and STAI between the built and natural environment, which showed that natural environment can lower the stress level. MC had the best effect on relieving physiological stress, whereas MCB is most successful in improving emotional state and reducing anxiety. Broad-leaved forest and mixed forest significantly affected the DBP and vigor level of the subjects, respectively. While coniferous forest did significantly increase the concentration of salivary cortisol in subjects. The study confirmed that compared to the built environment, the natural environment can relieve the human body's physical and psychological stress and negative emotions, while significantly increasing vitality. And different plant communities also have different effects on the physiological and psychological indicators of the subjects. These results will provide scientific basis for the construction and improvement of urban green space environment.

Physiological adjustment effect of visual stimulation by fresh rose flowers on sympathetic nervous activity

Introduction

As modern societies are often stressful due to urbanization and artificialization, the physiological relaxing effects of natural environments or nature-derived stimuli on humans have attracted attention and scientific data are being accumulated. It is known that there is inter-individual variation in these effects. The study aim was to apply the law of initial values to investigate the physiological adjustment effect of viewing fresh roses on sympathetic nervous activity.

Methods

In this crossover study, a total of 214 high school students, office workers, healthcare workers, and elderly people were analyzed. The participants viewed fresh roses in a vase for 4 min. In the control condition, participants did not view any fresh roses during the period. To offset any order effect, participants received visual stimuli in the order of fresh roses then the control (no fresh roses) or the control and then fresh roses. ln (LF/HF) of heart rate variability (HRV) obtained from a-a interval measurements using an acceleration plethysmograph and used as an index of sympathetic nervous activity. The initial value was ln (LF/HF) of HRV during the control viewing (no fresh roses), and the change value was ln(LF/HF) of HRV during visual stimulation by fresh roses minus the control viewing.

Results and Discussion

The correlation between the two was assessed by determining Pearson's correlation coefficient r, which was significantly negative. A physiological adjustment effect was observed such that participants with high initial sympathetic nervous activity showed a decrease in activity after visual stimulation with fresh roses, whereas participants with low initial activity showed an increase.

Is altitude a determinant of the health benefits of nature exposure? A systematic review and meta-analysis

Introduction

Nature exposure is a widely accepted option for promoting public health owing to the recent surge of scientific evidence. However, the actual settings to facilitate this initiative is yet to be extensively reviewed. In this systematic review, we have aimed to provide an up-to-date summary of interventional studies investigating the psycho-physiological effects of forests and urban forests, including details on their physical settings, and investigate an effect-modifying role of altitude and summarize data on the magnitude and shape of the association.

Methods

A keyword search using five electronic academic databases (PubMed, Embase, PsycINFO, Web of Science, and Scopus) was conducted to identify relevant articles published in English from the inception year to the end of February 2022. The methodological quality was evaluated using the ROBINS-I or ROB2 tool, depending on the study design. Meta-regression and random effects model were jointly used to examine the relationship between altitude and health outcomes.

Results

We included 27 eligible studies and 31 cases extracted from 19 studies were used for the meta-analysis. In the meta-regression, we observed a non-linear association between altitude and psycho-physiological effects. Altitude had a positive quadratic association with anxiety (p < 0.000, adjusted R ² = 96.79%), depression (p < 0.000, adjusted R ² = 98.78%), and fatigue (p < 0.000, adjusted R ² = 64.74%) alleviating effects. Conversely, altitude demonstrated a negative non-linear association with the blood pressure-lowering effect (p = 0.009, adjusted R ² = 32.83%). Additionally, the thermal index (THI) and illuminance (lx) levels were significantly associated with effect sizes of psychological restoration.

Discussion

This review provides moderate-certainty evidence for an effect-modifying role of altitude. The meta-regression results suggested the optimal and minimal altitude ranges for psychological restoration and physiological relaxation, respectively. Despite some limitations, the study findings provide a significant basis for utilizing altitude, which is easily accessible and simple, to promote the health benefits of nature-based initiatives.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022310894, identifier: CRD42022310894.

Nature Exposure and Its Effects on Immune System Functioning: A Systematic Review

Given the drastic changes in our lifestyles and ecosystems worldwide, the potential health effects of natural environments have grown into a highly pervasive topic. Recent scientific findings suggest beneficial effects from nature exposure on human immune responses. This review aims at providing a comprehensive overview of literature published on immunomodulatory effects of nature exposure by inhalation of natural substances. A systematic database search was performed in SCOPUS and PubMed. The quality and potential bias of included studies (n = 33) were assessed by applying the EPHPP (Effective Public Health Practice Project) tool for human studies and the ARRIVE (Animal Research: Reporting of In Vivo Experiments) and SYRCLE (Systematic Review Centre for Laboratory Animal Experimentation) tools for animal studies. The synthesis of reviewed studies points to positive effects of nature exposure on immunological health parameters; such as anti-inflammatory, anti-allergic, anti-asthmatic effects or increased NK (natural killer) cell activity. Decreased expression of pro-inflammatory molecules, infiltration of leukocytes and release of cytotoxic mediators are outcomes that may serve as a baseline for further studies. However, partially weak study designs evoked uncertainties about outcome reproducibility and key questions remain open concerning effect sizes, duration of exposure and contributions of specific vegetation or ecosystem types.

How Should Forests Be Characterized in Regard to Human Health? Evidence from Existing Literature

The potential of forests as a source of health has been addressed by the scientific community and is now being considered in national forest strategies, management plans and policies. Studies identifying the mechanisms by which forest characteristics may induce these effects on human health are nevertheless scarce. This systematic review of literature on forests and human health with real-life human exposure was conducted to assess the extent to which forests have been studied and described in detail and the extent to which relationships between forest variables and health effects have been reported. The analysis underlines the lack of forest descriptions in 19.35% of the 62 studies selected for review as well as the high heterogeneity of forest variables’ description. Patterns among the articles could not be identified correlating the broader forest variable (forest type) and the most studied health variables identified (blood pressure, pulse rate or/and cortisol levels). These findings, together with previous ex situ researches, suggest the need to ameliorate and incorporate more accurate descriptions of forest variables within human health studies to provide data for forest management and the potential use of these habitats for preventive medicine and clinical practice guidelines.

Medical empirical research on forest bathing (Shinrin-yoku): a systematic review

Aims

This study focused on the newest evidence of the relationship between forest environmental exposure and human health and assessed the health efficacy of forest bathing on the human body as well as the methodological quality of a single study, aiming to provide scientific guidance for interdisciplinary integration of forestry and medicine.

Method

Through PubMed, Embase, and Cochrane Library, 210 papers from January 1, 2015, to April 1, 2019, were retrieved, and the final 28 papers meeting the inclusion criteria were included in the study.

Result

The methodological quality of papers included in the study was assessed quantitatively with the Downs and Black checklist. The methodological quality of papers using randomized controlled trials is significantly higher than that of papers using non-randomized controlled trials (p < 0.05). Papers included in the study were analyzed qualitatively. The results demonstrated that forest bathing activities might have the following merits: remarkably improving cardiovascular function, hemodynamic indexes, neuroendocrine indexes, metabolic indexes, immunity and inflammatory indexes, antioxidant indexes, and electrophysiological indexes; significantly enhancing people’s emotional state, attitude, and feelings towards things, physical and psychological recovery, and adaptive behaviors; and obvious alleviation of anxiety and depression.

Conclusion

Forest bathing activities may significantly improve people’s physical and psychological health. In the future, medical empirical studies of forest bathing should reinforce basic studies and interdisciplinary exchange to enhance the methodological quality of papers while decreasing the risk of bias, thereby raising the grade of paper evidence.

Physiological and Psychological Effects of Viewing Forests on Young Women

Research Highlights: This study demonstrated that viewing forest landscapes induced physical and mental health benefits on young women. Background and Objectives: The health-promoting effects of spending time in forests have received increasing attention; however, there is a lack of evidence-based research investigating the effects of spending time in forests on women. This study aimed to evaluate the physiological and psychological effects of viewing forest landscapes on young women. Materials and Methods: The experiments were conducted in six forests and six city areas and included 65 women (mean age, 21.0 ± 1.3 years). Participants viewed a forest and a city area for 15 min, during which their heart rate variability and heart rate were measured continuously. Blood pressure and pulse rate were measured before and after the viewing. After the viewing, participants’ psychological responses were assessed using the modified semantic differential method, Profile of Mood States (POMS), and the State–Trait Anxiety Inventory (STAI). Results: Compared with viewing city areas, viewing forest landscapes was associated with significantly higher parasympathetic nervous activity and lower sympathetic nervous activity and heart rate. Moreover, scores of the comfortable, relaxed, and natural parameters and vigor subscales of POMS were significantly higher with forest viewing. The scores of negative feelings, such as tension–anxiety, depression–dejection, anger–hostility, fatigue, and confusion, were significantly lower, as were scores for the total mood disturbance observed using POMS and the anxiety dimension observed using STAI. Conclusions: Viewing forest landscapes resulted in physiological and psychological relaxations in young women.

[Reviewing the psychological and physical health effects of forests]

Civilization illnesses today impact, and will impact in the future, everyday life of people, particularly in high-income countries. Consequences are loss in life expectancy, reduction of quality of life as well as rising economic loads. The positive effects of stays and visits in natural environments on human well-being are known for a long time. Particularly, there are many indications that forest stays have health-promoting effects. This narrative review of the literature presents the current state of the research on health-promoting effects of forest exposure. Forest exposure has positive health effects on the cardiovascular system, the immune system and on mood. Especially in the context of stress reduction, forest exposure seems to have positive influences. However, little can be concluded about the extent of these positive effects, as most studies work without control environment or control groups. Moreover forest exposure is often associated with physical activity which is also known to have health benefits. Against the background of the positive health promoting trend further research should be carried out.

Psycho-Physiological Effects of a Peony-Viewing Program on Middle-Aged and Elderly Individuals at Different Phenological Stages

To address the question of whether the behavior of humans to view different phenological peony flowers has various effects on their physical and mental parameters, we investigated psycho-physiological responses of 74 participants (61.3 ± 10.78 years old) to environments of pre- and post-viewing tree peonies at four stages, including the exhibition leaf stage (ELS), initial bloom stage (IBS), full bloom stage (FBS), and terminal bloom stage (TBS). Physiological factors were examined using systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), fingertip pulse (FP), blood oxygen saturation (SpO₂), and psychological evaluation, which was carried out using the Profile of Mood States (POMS) and State–Trait Anxiety Inventory (STAI). The results indicated that the SBP, DBP, HR, and FP levels of participants were significantly reduced after viewing tree peonies, whereas no remarkable alterations in SpO₂ were found. The POMS scores of anger–hostility (A–H), fatigue–inertia (F–I), tension–anxiety (T–A), confusion–bewilderment (C–B), and depression–dejection (D–D) were significantly lower, but of vigor–activity (V–A) was higher post-viewing than pre-viewing. Furthermore, participants exhibited markedly decreased anxiety levels according to the STAI. Notably, the changes in measurement indices were more pronounced at the FBS. Our studies demonstrated that a short peony-viewing program, especially at the FBS with completely opened and large tree peony flowers, would be a promising therapeutic method for improving physiological functions as well as an effective psychological relaxation strategy for middle-aged and elderly individuals.

Effects of Walking in a Forest on Young Women

The effects of forest activities on health promotion have received increasing attention. The aim of this study was to evaluate the physiological and psychological effects of brief walks in forests on young women. The experiments were conducted in 6 forests (test) and 6 city areas (control). Overall, 12 participants in each area (60 participants in total, mean age: 21.0 ± 1.3 years) were instructed to walk in a forest and a city area for approximately 15 min; simultaneously, their heart rate variability, heart rate, blood pressure, and pulse rate were measured to quantify their physiological responses to walking. The modified semantic differential method, Profile of Mood States (POMS), and the State–Trait Anxiety Inventory (STAI) were used to determine their psychological responses. Walking in a forest was associated with significantly higher parasympathetic nervous activity and lower sympathetic nervous activity and heart rate. In addition, scores for the comfortable, relaxed, and natural parameters and vigor subscale of POMS were significantly higher, whereas scores for negative feelings, such as tension–anxiety, depression–dejection, anger–hostility, fatigue, and confusion, were significantly lower, as were the total mood disturbance of POMS and the anxiety dimension of the STAI. The subjective evaluations were generally in accordance with the physiological responses. A brief walk in a forest resulted in physiological and psychological relaxation effects in young women.

The Effects of a Short Forest Recreation Program on Physiological and Psychological Relaxation in Young Polish Adults

Forest recreation is an activity that could be successfully used to alleviate negative symptoms of stress in individuals. Multiple positive psychological and physiological effects have been described in the literature, especially regarding works describing research from Asian countries such as Japan, Korea, and Taiwan. In East-Central Europe, however, the effectuality of forest recreation has not been addressed in scientific research. Thus, a special recreation program was developed, and its usability was examined with the involvement of 21 young Polish adults. A pre- and post-test design was used, wherein four psychological questionnaires were applied (Profile of Mood States, Positive and Negative Affect Schedule, Restorative Outcomes Scale, Subjective Vitality Scale), and physiological measures were assessed (pulse rate, blood pressure) before and after the program. A field study was also conducted at the nature reserve Redykajny, near the suburban forest of the city of Olsztyn. The recreational program had a significant impact on psychological and physiological parameters. After recreation, the negative mood markers of the negative affect decreased and the positive affect, including restoration and vitality, increased. Furthermore, pulse rates, systolic blood pressures, and mean arterial pressures of the participants were significantly lower after the program. These results reveal that the short forest recreation program may be effective in reducing negative symptoms of stress.

Psychological Benefits of Walking through Forest Areas

This study aimed to clarify the psychological benefits of brief walks through forest areas. In addition, we aimed to examine the associations between psychological responses and trait anxiety levels. Five-hundred-and-eighty-five participants (mean age, 21.7 ± 1.6 years) were instructed to walk predetermined courses through forest (test) and city (control) areas for 15 min. The Profile of Mood State (POMS) questionnaire and State-Trait Anxiety Inventory were used to assess participants’ psychological responses and trait anxiety levels, respectively. The results revealed that walking through forest areas decreased the negative moods of “depression-dejection”, “tension-anxiety”, “anger-hostility”, “fatigue”, and “confusion” and improved the participants’ positive mood of “vigor” compared with walking through city areas. Furthermore, a significant correlation was found between participants’ trait anxiety levels and their changes in the subscale of “depression-dejection” of POMS after walking through forest areas. A more effective reduction in the feeling of “depression-dejection” after walking through forest areas was observed for participants with high trait anxiety levels than for those with normal and low trait anxiety levels. This study showed the psychological benefits of walking through forest areas and identified a significant correlation between psychological responses to walking through forests and trait anxiety levels.

Blood pressure-lowering effect of Shinrin-yoku (Forest bathing): a systematic review and meta-analysis

Background

Shinrin-yoku (experiencing the forest atmosphere or forest bathing) has received increasing attention from the perspective of preventive medicine in recent years. Some studies have reported that the forest environment decreases blood pressure. However, little is known about the possibility of anti-hypertensive applications of Shinrin-yoku. This study aimed to evaluate preventive or therapeutic effects of the forest environment on blood pressure.

Methods

We systematically reviewed the medical literature and performed a meta-analysis.Four electronic databases were systematically searched for the period before May 2016 with language restriction of English and Japanese. The review considered all published, randomized, controlled trials, cohort studies, and comparative studies that evaluated the effects of the forest environment on changes in systolic blood pressure. A subsequent meta-analysis was performed.

Results

Twenty trials involving 732 participants were reviewed. Systolic blood pressure of the forest environment was significantly lower than that of the non-forest environment. Additionally, diastolic blood pressure of the forest environment was significantly lower than that of the non-forest environment.

Conclusions

This systematic review shows a significant effect of Shinrin-yoku on reduction of blood pressure.

Electronic supplementary material

The online version of this article (doi:10.1186/s12906-017-1912-z) contains supplementary material, which is available to authorized users.

Effects of Short Forest Bathing Program on Autonomic Nervous System Activity and Mood States in Middle-Aged and Elderly Individuals

The present study investigated changes in autonomic nervous system activity and emotions after a short (2 h) forest bathing program in the Xitou Nature Education Area (XNEA), Taiwan. One hundred and twenty-eight (60.0 ± 7.44 years) middle-aged and elderly participants were recruited. Physiological responses, pulse rate, systolic and diastolic blood pressure, heart rate variability (HRV), and psychological indices were measured before and after the program. We observed that pulse rate, systolic and diastolic blood pressure were significantly lower after the program, which indicated physiological benefits from stress recovery. The Profile of Mood States negative mood subscale scores of "tension-anxiety", "anger-hostility", "fatigue-inertia", "depression-dejection", and "confusion-bewilderment" were significantly lower, whereas the positive mood subscale score of "vigor-activity" was higher. Furthermore, participants exhibited significantly lower anxiety levels according to the State-Trait Anxiety Inventory. However, changes in sympathetic and parasympathetic nerve activity were nonsignificant. Our study determined that the short forest bathing program is a promising therapeutic method for enhancing heart rate and blood pressure functions as well as an effective psychological relaxation strategy for middle-aged and elderly individuals.

Experimental Study on the Health Benefits of Garden Landscape

To mitigate the negative effects of modern cities on health, scientists are focusing on the diverse benefits of natural environments; a conceptual approach to use gardens for promoting human health is being attempted. In this study, the effects of the visual landscape of a traditional garden on psychological and physiological activities were investigated. Eighteen male and female adults participated in this indoor experiment (mean age, 26.7 years). Twelve different landscape images for city and garden were presented continuously for 90 s. In the time series changes of oxygenated hemoglobin (O₂Hb), different patterns of changes were observed between the city and garden. The mean O₂Hb values increased for the city landscapes, whereas they decreased for the garden landscapes both in the left and right prefrontal cortices. Significant differences in the negative psychological states of tension, fatigue, confusion, and anxiety were observed between the city and garden landscapes. Important differences in the physiological and psychological responses to the two different landscapes were also detected between male and female participants, providing valuable clues to individual differences in the health benefits of natural landscapes. To validate the use of gardens as a resource for promoting health in urban dwellers, further scientific evidence, active communication, and collaboration among experts in the relevant field are necessary.

Physiological Effects of Nature Therapy: A Review of the Research in Japan

Humans have evolved into what they are today after the passage of 6-7 million years. If we define the beginning of urbanization as the rise of the industrial revolution, less than 0.01% of our species' history has been spent in modern surroundings. Humans have spent over 99.99% of their time living in the natural environment. The gap between the natural setting, for which our physiological functions are adapted, and the highly urbanized and artificial setting that we inhabit is a contributing cause of the "stress state" in modern people. In recent years, scientific evidence supporting the physiological effects of relaxation caused by natural stimuli has accumulated. This review aimed to objectively demonstrate the physiological effects of nature therapy. We have reviewed research in Japan related to the following: (1) the physiological effects of nature therapy, including those of forests, urban green space, plants, and wooden material and (2) the analyses of individual differences that arise therein. The search was conducted in the PubMed database using various keywords. We applied our inclusion/exclusion criteria and reviewed 52 articles. Scientific data assessing physiological indicators, such as brain activity, autonomic nervous activity, endocrine activity, and immune activity, are accumulating from field and laboratory experiments. We believe that nature therapy will play an increasingly important role in preventive medicine in the future.

Physiological and Psychological Effects of a Forest Therapy Program on Middle-Aged Females

The natural environment is increasingly recognized as an effective counter to urban stress, and "Forest Therapy" has recently attracted attention as a relaxation and stress management activity with demonstrated clinical efficacy. The present study assessed the physiological and psychological effects of a forest therapy program on middle-aged females. Seventeen Japanese females (62.2 ± 9.4 years; mean ± standard deviation) participated in this experiment. Pulse rate, salivary cortisol level, and psychological indices were measured on the day before forest therapy and on the forest therapy day. Pulse rate and salivary cortisol were significantly lower than baseline following forest therapy, indicating that subjects were in a physiologically relaxed state. Subjects reported feeling significantly more "comfortable," "relaxed," and "natural" according to the semantic differential (SD) method. The Profile of Mood State (POMS) negative mood subscale score for "tension-anxiety" was significantly lower, while that for "vigor" was significantly higher following forest therapy. Our study revealed that forest therapy elicited a significant (1) decrease in pulse rate, (2) decrease in salivary cortisol levels, (3) increase in positive feelings, and (4) decrease in negative feelings. In conclusion, there are substantial physiological and psychological benefits of forest therapy on middle-aged females.