The Inverse Association between the Frequency of Forest Walking (Shinrin-yoku) and the Prevalence of Insomnia Symptoms in the General Japanese Population: A Japan Multi-Institutional Collaborative Cohort Daiko Study

Since a single forest walk (Shinrin-yoku or forest bathing) session is reported to improve sleep temporarily, occasional forest walks may have a positive effect on daily sleep. Therefore, this study aimed to examine whether more frequent forest walking is associated with better daily sleep conditions. Data from the second survey of the Japan Multi-Institutional Collaborative Cohort (J-MICC) Daiko Study conducted among residents of Nagoya City, Japan, were used. The study design was a cross-sectional study. In total, 2044 participants (529 men and 1515 women; age, mean ± standard deviation: 58.8 ± 9.9 years) were included in the analysis. Frequent forest walks were associated with a low percentage of insomnia symptoms (Insomnia Severity Index ≥10) in women, but not in men. The adjusted odds ratio for the group that rarely took forest walks with reference to the group that engaged in the activity once a month or more often was 2.04 (95% confidence interval: 1.29-3.23) in women. Forest walk frequency was not significantly associated with sleep duration or sleep efficiency as measured by actigraphy in either men or women. In conclusion, the results suggested that increasing the frequency of forest walks or Shinrin-yoku may be effective in preventing insomnia in women.

Spending time in the forest or the field: qualitative semi-structured interviews in a randomized controlled cross-over trial with highly sensitive persons

Introduction

The effects of spending time in forests have been subject to investigations in various countries around the world. Qualitative comparisons have been rarely done so far.

Methods

Sixteen healthy highly sensitive persons (SV12 score ≥ 18) aged between 18 and 70 years were randomly assigned to groups spending 1 h in the forest and in the field at intervals of one week. Semi-structured interviews were conducted after each intervention and analyzed using a mixed-methods approach of content analysis and grounded theory.

Results

Both natural environments induced feelings of inner calmness, inner cleansing, joy, freedom, connectedness, strengthening qualities, and heightened body awareness. The forest environment additionally offered emotional shelter, and showed advantages in promoting inner strength and self-concentration.

Discussion

People with previous negative experiences in the forest may feel safer in fields because of the wider view and better overview. Important preconditions are enough time and the absence of a judgmental authority. The two environments induced in part different but also similar emotions which might be useful to promote psychological well-being differentially.

A Forest Bathing Intervention in Adults with Intellectual Disabilities: A Feasibility Study Protocol

Forest bathing practices benefit individuals' physical and mental health. A growing number of published studies provide evidence of such effects in diverse populations and contexts. However, no literature has been found that evaluates the effects of forest bathing on people with intellectual disabilities. In this paper, we present a quasi-experimental pre-post protocol for assessing the preliminary efficacy and feasibility of a forest bathing intervention in a group of adults with intellectual disability. An 11-weekly session program will be applied in the forests of the Ollo Valley, Navarre (Spain). The preliminary efficacy outcomes will be blood pressure, psycho-physiological coherence parameters and quality of life. The feasibility of the intervention will be assessed through data on barriers and facilitators of the implementation process and indicators of environmental comfort (physiological equivalent temperature and thermic perception). This study offers an opportunity for people with intellectual disabilities to benefit from a forest bathing intervention and explore its effects not only on their quality of life, but also on the improvement in their physiological and psychological state. This feasibility study is an essential step to explore crucial aspects for a future full-scale trial.

Effects of forest environment (Shinrin-yoku/Forest bathing) on health promotion and disease prevention -the Establishment of "Forest Medicine"

Humans have enjoyed forest environments for ages because of the quiet atmosphere, beautiful scenery, mild climate, pleasant aromas, and fresh, clean air. In Japan, since 2004, serial studies have been conducted to investigate the effects of forest environments (Forest bathing/Shinrin-yoku) on human health. My research team has established a new medical science called Forest Medicine. The Forest Medicine is a new interdisciplinary science, belonging to the categories of alternative medicine, environmental medicine and preventive medicine, which studies the effects of forest environments (Forest bathing/Shinrin-yoku) on human health. It has been reported that Forest bathing/Shinrin-yoku has the following beneficial effects on human health:1 Shinrin-yoku increases human natural killer (NK) activity, the number of NK cells, and the intracellular levels of anti-cancer proteins, suggesting a preventive effect on cancers. 2 Shinrin-yoku reduces blood pressure and heart rate showing preventive effect on hypertension and heart diseases. 3 Shinrin-yoku reduces stress hormones, such as urinary adrenaline and noradrenaline and salivary/serum cortisol contributing to stress management. 4 Shinrin-yoku increases the activity of parasympathetic nerves and reduces the activity of sympathetic nerves to stabilize the balance of autonomic nervous system. 5 Shinrin-yoku improve sleep. 6 Shinrin-yoku increases the levels of serum adiponectin and dehydroepiandrosterone sulfate. 7 In the Profile of Mood States (POMS) test, Shinrin-yoku reduces the scores for anxiety, depression, anger, fatigue, and confusion, and increases the score for vigor, showing preventive effects on depression. 8 Shinrin-yoku may apply to rehabilitation medicine 9 Shinrin-yoku in city parks also has benefits on human health. 10 Shinrin-yoku may have preventive effect on COVID-19 by boosting immune function and by reducing mental stress.Taken together, these findings suggest that Shinrin-yoku may have potential preventive effects on non-communicable diseases.

Effects of forest bathing (shinrin-yoku) on serotonin in serum, depressive symptoms and subjective sleep quality in middle-aged males

BACKGROUND

We previously found that a forest bathing (shinrin-yoku) program significantly reduced the scores for depression, anxiety, anger, fatigue, and confusion and increased the score for vigor in the profile of mood states (POMS) test and showed a potential preventive effect on the depressive status in both males and females. In the present study, we investigated the effects of a forest bathing program on the level of serotonin in serum, depressive symptoms and subjective sleep quality in middle-aged males.

METHODS

Twenty healthy male subjects aged 57.3 ± 8.4 years were selected after obtaining informed consent. These subjects took day trips to a forest park, the birthplace of forest bathing in Japan named Akasawa Shizen Kyuyourin, Agematsu, Nagano Prefecture (situated in central Japan), and to an urban area of Nagano Prefecture as a control in June 2019. On both trips, they walked 2.5 km for 2 hours each in the morning and afternoon on Saturday and Sunday, respectively. Blood was sampled in the afternoon before and after each trip. Concentrations of serotonin and lactic acid in serum were measured. The POMS test and a questionnaire for subjective sleep quality were conducted before and after the trips. Ambient temperature and humidity were monitoring during the trips. The Ethics Committees of the Nippon Medical School and Nagano Prefectural Kiso Hospital approved this study.

RESULTS

The forest bathing program significantly increased level of serotonin in serum, and significantly increased the score for vigor and decreased the score for fatigue in the POMS test. The forest bathing program also improved the sleepiness on rising and feeling refreshed (recovery from fatigue) in the Oguri-Shirakawa-Azumi sleep inventory MA version (OSA-MA).

CONCLUSIONS

Taken together, the present study suggests that forest bathing may have potential preventive effects on depression (depressive status).

Forest Manners Exchange: Forest as a Place to Remedy Risky Behaviour of Adolescents: Mixed Methods Approach

This paper evaluates the impact of the forest environment on aggressive manifestations in adolescents. A remedial educative programme was performed with 68 teenagers from institutions with substitute social care with diagnoses F 30.0 (affective disorders) and F 91.0 (family-related behavioural disorders), aged 12–16 years. Adolescents observed patterns of prosocial behaviour in forest animals (wolves, wild boars, deer, bees, ants, squirrels and birds), based on the fact that processes and interactions in nature are analogous to proceedings and bonds in human society. The methodology is based on qualitative and quantitative research. Projective tests (Rorschach Test, Hand Test, Thematic Apperception Test) were used as a diagnostic tool for aggressive manifestations before and after forest therapies based on Shinrin-yoku, wilderness therapy, observational learning and forest pedagogy. Probands underwent 16 therapies lasting for two hours each. The experimental intervention has a statistically significant effect on the decreased final values relating to psychopathology, irritability, restlessness, emotional instability, egocentrism, relativity, and negativism. Forest animals demonstrated to these adolescents ways of communication, cooperation, adaptability, and care for others, i.e., characteristics without which no community can work.

Mindfulness and Shinrin-Yoku: Potential for Physiological and Psychological Interventions during Uncertain Times

Mindfulness and Shinrin-yoku (SY) translated as forest bathing, is potentially effective to alleviate mental health issues related to the COVID-19 pandemic and beyond. The purpose of this article is to provide a translational and pragmatic approach to understanding mindfulness in the context of SY and psychological wellbeing through a rapid review of the literature. The background of mindfulness and SY practice are discussed and the emotional, neuroendocrine, and neurobiological responses are examined. Next, a rapid review of the literature examined six studies, published between 2010 and 2020 to determine what is known regarding the relationship between SY, mindfulness, and psychological wellbeing. The studies included 21-360 participants with a mean age of 20-55 years. The results demonstrated a significant positive correlation between nature, mindfulness, and measures of psychological wellbeing. During uncertain events, including COVID-19, weaving mindfulness with SY may be specifically important to at-risk groups, those experiencing depression, loneliness, and social isolation, and at-risk populations such as college students, veterans, and professionals with high levels of stress. The goal of this review is to provide a thorough background and support of this cost-effective modality to promote overall psychological wellbeing as a preventative measure to those at risk or experiencing psychological illnesses.

Commentary: Suggesting Shinrin-yoku (forest bathing) for treating addiction

Shinrin-yoku ('') (i.e., forest bathing), a Japanese wellbeing practice, aims to harmonise a person with a forest by bathing in the forest mindfully using our five senses (Miyazaki, 2018). Practitioners can choose whatever they like to focus on in the forest: different colours of leaves, the sounds of streams, or the warmth of sunshine beaming between leaves. Since the birth of this practice in 1982, shinrin-yoku has been widely used in the Japanese clinical fields (Hansen, Jones, & Tocchini, 2017). Recently, this healing practice has received attention from healthcare practitioners and researchers worldwide (Wen, Yan, Pan, Gu, & Liu, 2019). In this commentary, we will discuss limitations of the current shinrin-yoku research, and how future research can be conducted to appraise the effects of shinrin-yoku on addiction.

Effects of forest bathing on pre-hypertensive and hypertensive adults: a review of the literature

The aim in this literature review was (1) to explore the physiologically and psychologically therapeutic benefits of forest bathing on adults suffering from pre-hypertension or hypertension, and (2) to identify the type, duration, and frequency of an effective forest bathing intervention in the management of pre-hypertension and hypertension, so as to provide directions for future interventions or research. The electronic databases PubMed, Cochrane Library, CINAHL, PsyINFO, and the China Academic Journals (CAJ) offered through the Full-text Database (CNKI) were searched for relevant studies published from the inception of the databases to April 2019. Of the 364 articles that were identified, 14 met the criteria for inclusion in this review. The synthesis of the findings in the included studies revealed that forest bathing interventions were effective at reducing blood pressure, lowering pulse rate, increasing the power of heart rate variability (HRV), improving cardiac-pulmonary parameters, and metabolic function, inducing a positive mood, reducing anxiety levels, and improving the quality of life of pre-hypertensive or hypertensive participants. Forest walking and forest therapy programs were the two most effective forest bathing interventions. Studies reported that practicing a single forest walking or forest therapy program can produce short-term physiological and psychological benefits. It is concluded that forest bathing, particularly forest walking and therapy, has physiologically and psychologically relaxing effects on middle-aged and elderly people with pre-hypertension and hypertension.

Frequency of forest walking is not associated with prevalence of hypertension based on cross-sectional studies of a general Japanese population: a reconfirmation by the J-MICC Daiko Study

Forest walking or Shinrin-yoku is a health promotion activity in Japan. Although some studies have reported the acute effects of walking a few hours in forested areas in reducing blood pressure level compared to other environments, studies investigating whether successive walking has long-term effects in lowering blood pressure levels or lowering prevalence of hypertension are rare. This study aimed to reconfirm the presence or absence of an association between the frequency of forest walking and prevalence of hypertension in a Japanese population. This J-MICC Daiko Study was conducted targeting residents in Nagoya City. A total of 5,109 participants (1,452 men and 3,657 women; age, mean ± standard deviation: 52.5 ± 10.3 years) were included in the analysis. Age-adjusted blood pressure level by frequency of forest walking was not significant. After adjusting for age and lifestyle, the adjusted odds ratios (aORs) of the most frequent group (n=88, 1.7%; once a week or more group) relative to the less than once a month group (n=4,558, 89.2%) for prevalence of hypertension were not also significant [0.80 (95% CI: 0.40–1.62) for men and 1.48 (95% CI: 0.73–3.00) for women]. This study reconfirmed that either lowering blood pressure level or lowering the prevalence of hypertension is not associated with frequency of forest walking, similar to the results of our previous J-MICC Shizuoka Study. Given that these two studies were cross-sectional studies, cohort studies investigating the causal relationship are required to evaluate the effect of frequent forest walking on the prevention of hypertension.

The Effects of a Forest Therapy Programme on Mental Hospital Patients with Affective and Psychotic Disorders

The positive effect of forest bathing on the mental health and wellbeing of those suffering from post-traumatic stress disorder or experiencing stress has been proven. It is not known, however, how 'forest therapy' affects the mental health of people who are treated in a psychiatric hospital for affective or psychotic disorders. Potentially, forest therapy could bring many benefits to these people. To test the potential effectiveness of this therapy, a quasi-experiment was carried out in a psychiatric hospital in Olsztyn (north Poland). In the summer and autumn of 2018, the patients of the psychiatric hospital in Olsztyn participated in forest therapy interventions. The proposed forest therapy consisted of participating in one hour and forty-five minutes walks under the supervision of a therapist. Subjects filled out the Profile of Mood States Questionnaire (POMS) and the State Trait Anxiety Inventory (STAI-S) before and after the study. In the case of a group of patients with affective disorders, forest therapy had a positive effect on nearly all POMS scale subscales, with the exception of the 'anger-hostility' subscale, which did not change its values significantly after the intervention. In these patients, the greatest impacts were noted in the subscales 'confusion' and 'depression-dejection'; the level of anxiety measured with the STAI-S scale also significantly decreased. In the case of patients with psychotic disorders, the values of the 'confusion' and 'vigour' subscales and the STAI-S scale exhibited the greatest changes. These changes were positive for the health of patients. Regarding the 'fatigue' subscale, no significant changes were observed in patients with psychotic disorders. The observed changes in psychological indicators in psychiatric hospital patients with both kinds of disorders indicate that the intervention of forest therapy can positively affect their mental health. The changes observed in psychological indicators were related to the characteristics of the given disorder.

Relation between Psychological Restorativeness and Lifestyle, Quality of Life, Resilience, and Stress-Coping in Forest Settings

Previous research has mainly dealt with the physiological and psychological restorative effects of the forest environment. However, comparatively few studies have focused on how the traits and attributes of individuals (individual traits) affect the restorative effects of the forest environment. In this study, we examined the relationships between the psychological restorative effects offered by perceived restorativeness of outdoor settings and the individual traits. Then, we investigated the relationships between the restorative indicators that are useful in examining the restorative properties (i.e., the Perceived Restorativeness Scale (PRS); seven indicators in total), the psychological restorative effect (Profile of Mood States (POMS), Restorative Outcome Scale (ROS), positive and negative affect schedule (PANAS), and Subjective Vitality Scale (SVS); 10 indicators in total), and the individual trait indicators that could be used to investigate individual traits (Development of Health and Life Habit Inventory for lifestyle, Lazarus-type Stress Coping Inventory for stress coping, World Health Organization Quality of Life Assessment 26 for quality of life (QOL), and Sukemune-Hiew Resilience test for resilience; 28 indicators in total) in forest and urban settings. Respondents consisted of 46 male students in their twenties. A short-term experiment was conducted using the same method in both environmental settings. We then analyzed the intrinsic restorative properties and the restorative effects of the settings and referred to prior research to determine the restorative effects. Furthermore, we analyzed the relationship between the restorative indicators and the individual trait indicators by correlation analysis and multiple regression (step-wise) analysis. These new findings were obtained: (1) the forest setting was a restorative environment with a higher restorative effect than the urban setting; (2) although the forest setting had a higher restorative effect than the urban setting, and the influence of individual traits was small; (3) in the forest setting, the relationship between the restorative indicators and individual traits indicators were arranged; (4) distancing (Stress coping), psychological health (QOL), and satisfaction with living environment (QOL) were likely important indicators that are related to the restorative effects in the forest setting.

Management Effectiveness of a Secondary Coniferous Forest for Landscape Appreciation and Psychological Restoration

We investigated the influence of forest management on landscape appreciation and psychological restoration in on-site settings by exposing respondents to an unmanaged, dense coniferous (crowding) forest and a managed (thinned) coniferous forest; we set the two experimental settings in the forests of the Fuji Iyashinomoroi Woodland Study Center. The respondents were individually exposed to both settings while sitting for 15 min and were required to answer three questionnaires to analyze the psychological restorative effects before and after the experiment (feeling (the Profile of Mood States), affect (the Positive and Negative Affect Schedule), and subjective restorativeness (the Restorative Outcome Scale). To compare landscape appreciation, they were required to answer another two questionnaires only after the experiment, for scene appreciation (the semantic differential scale) and for the restorative properties of each environment (the Perceived Restorativeness Scale). Finally, we obtained these findings: (1) the respondents evaluated each forest environment highly differently and evaluated the thinned forest setting more positively; (2) the respondents' impressions of the two physical environments did not appear to be accurately reflected in their evaluations; (3) forest environments have potential restorative effects whether or not they are managed, but these effects can be partially enhanced by managing the forests.