Abstract
Virtual Forest Bathing as Practical Way to Connect to and Benefit from Nature: What Would E.O. Wilson Say?
Director
Osher Center for Integrative Medicine
Harvard Medical School and Brigham and Women's Hospital
As I write this piece, I am reflecting on the recent passing of Prof. E.O. Wilson, one of the most prominent evolutionary biologists of the past 100 years and champion for conservation of biological diversity. I had the privilege of serving as a teaching fellow with him during my PhD training in Evolutionary Biology at Harvard University. Among many landmark books written by Prof. Wilson, Biophilia put forward the notion that humans have an innate tendency to affiliate with the natural world as a result of our biocultural evolution. This tendency may help explain the growing evidence for robust benefits to physical and psychosocial health derived from even short exposures to nature, and the growing popularity of practices such as forest bathing, and horticultural and animal therapies.
Sadly, the combination of urbanization, destruction and degradation of natural environments, and lifestyles that increasingly involve more interaction with technology than biology has decreased society's access to, and contact with, nature. Moreover, for many, this disconnection has been exacerbated by COVID-19. Surveys support that COVID-related reductions in nature exposure are linked to increased experience of anxiety and depression during lockdowns.
Virtual reality (VR) leverages computer technology to create a simulated environment through placing the user inside an experience. Through simulation, and stimulation of multiple senses, such as vision, hearing, and touch, the platform serves as a gatekeeper to an artificial world. VR has shown to be an effective tool for addressing mental health issues such as depression, pain, stress, and phobias. VR can even provide a training environment for mind–body practices such as Tai Chi, Yoga, and meditation. As an extension of telehealth, VR also has the advantages of improving access to health-related resources, including perhaps, limited access to natural environments.
Chan and colleagues at the Nanyang Technological University in Singapore conducted a provocative, timely, and rigorous pair of studies that cast light on these themes. They evaluated the impact of brief VR exposure to a natural environment versus an urban environment on psychological and physiological well-being.1 Study 1 included young adults (n = 30, avg age = 20.5 years). Study 2 included older adults (n = 22, avg age = 72.7). Both used a Unity VR platform. In the VR nature environment, participants walked along a path between trees in a forest with the sound of light wind. In the urban environment, participants walked along a path between buildings in a downtown area with the sound of white noise. The sequence of exposures for each individual was randomly chosen and separated by 1 week. After practice using the VR setup, exposure in each environment was 5 min in Study 1 and 3 min is Study 2.
Multiple design features, including statistical considerations, were well described and sound. Outcomes in Study 1 included the validated Positive and Negative Affect Schedule instrument. In addition, they included cardiovascular activity assessed with a portable electrocardiogram (ECG) device and used to calculate heart rate and root mean square of successive differences (RMSSD)—a time-domain measure of heart rate variability that reflects parasympathetic activation.
A particularly important outcome of this study was a 13-item connectedness to nature scale that measures the extent that an individual feels connected to the physical natural world. Two sample items for endorsement (1–5 scale) include “Right now, I feel as though I belong to the earth just as much as it belongs to me,” and “Right now, I am feeling deeply aware of how my actions affect the natural world.” Study 2 used a simplified battery of questions limited to single questions related to positive and negative affect, nature connectedness, and self-reported stress (all 1–5 numerical scales).
In brief, Study 1 found that negative affect was reduced and nature connectedness was increased by a brief exposure to virtual forest environments, whereas a time-matched exposure to virtual urban environments reduced positive affect. Moreover, a preplanned analysis suggests that nature connectedness mediated the relationship between VR exposure and negative (but not positive) affect. ECG data revealed a significant decrease in heart rate and a statistically nonsignificant trend toward greater RMSSD during the nature condition, both suggesting greater relaxation and increased parasympathetic activation. Study 2 observed increases in positive affect and nature connectedness, and decreases in perceived stress during the nature condition, and a decrease in nature connectedness in urban conditions. Mediation analyses also supported that nature connectedness underlies the relationship between VR exposure and positive affect.
My initial reaction to reviewing this article was quite mixed. First, what would preindustrial human cultures make of scientists today studying the impact of exposure to nature, especially as experienced through VR, on human well-being, connectedness to nature, and planetary health. I suspect it would be like asking a fish how they experience water. I wondered too what Prof. Wilson would think of the idea of using artificial VR environments to both connect to and benefit from nature.
With reflection, I came to the conclusion that the ultimate value of VR exposure to nature depends on how and why it is deployed. On the one hand, I shudder to think that some people would use these findings as evidence that the rapid degradation of natural environments may not be as detrimental as some fear. Perhaps virtual environments can substitute for real forests and nature, just like some argue that vitamins and food alternatives can substitute for sustainably grown vibrant food. But on the other hand, I can hear Prof. Wilson arguing that many other virtual tools that human society has evolved—art, poetry, books, and nature programs on television (including many of his own)—have been used to communicate the tangible and intangible values and healing power of nature. That outcomes suggesting marked increases in nature connectedness in this study occurred within 3–5 min of exposure to VR forests suggests, perhaps ironically, that technology might be a powerful tool to reconnect us to an unplugged natural world.
If such tools are used in concert with larger initiatives to preserve and increase access to such environments, for health of people and planet, then perhaps the ends justify the means. More practically, including VR exposure to nature in a larger planetary health campaign could afford benefit to people who live in highly developed areas, and/or for older or health-impaired adults with limited mobility. In addition, it could improve access to therapeutic aspects of natural environments during unusual times of isolation such as that caused by COVID-19.
Finally, analogous to experimentally controlled clinical trials, emerging VR technology enables for precise control over many exposure factors in virtual “natural” environments such as light, smell, sounds, temperature, and species of plants and animals. These provide an opportunity for better understanding how humans and their perceptions of nature have evolved. Knowing that, at heart, Prof. Wilson was even more of a curious geeky scientist than me, I believe he would give two thumbs up in support of this study and line of research.
For the Love of Nature: Nature Affinity and Deprivation in the Time of COVID Lockdown
Director of Clinical Research
Osher Center for Integrative Medicine
Harvard Medical School and Brigham and Women's Hospital
Director, Research Fellowship in Integrative Medicine
Division of General Medicine, Beth Israel Deaconess Medical Center
Nature affinity, our innate desire and need to be near nature, might be explained through the concept of biophilia, which describes man's relationship with the natural world through an evolutionary lens. Presumably, throughout human history, those who were more closely connected to nature (e.g., proximity to fresh water and vegetation, having an animal companion that could act as a protector) would have had evolutionary survival advantages. Man's nature affinity thus became inborn. We may be wired to connect to nature.
Not surprisingly, modern research seems to bear this out. We see the positive effects of nature on multiple dimensions of our health and well-being. However, when one looks critically at this literature, we find it contains important gaps. Much of our knowledge about effects of nature on health comes from observational studies using geospatial methods (satellite images and GPS) that analyze proximity and volume of residential greenspace. These studies often do not address multiple implicit sociobehavioral confounders. Other intervention studies typically consider only the “additive” effect of nature exposure.
For example, an intervention study might compare the usual urban environment (city living) with the added exposure of a natural environment (green park). The reverse scenario, empirically studying the impact of withdrawal from nature has been more elusive and perhaps impractical. Thus, little is known regarding individual perceptions of nature, nature affinity, and the very interesting corollary construct of nature deprivation (the emotional sense of withdrawal and perceived deficiency of nature exposure) and the role of these in impacting well-being.
The start of the COVID-19 pandemic created a natural experimental circumstance and a unique opportunity to study the impact of nature in a forced lockdown environment. The study by Tomasso and colleagues from the Harvard T.H. Chan School of Public Health took advantage of this opportunity to better understand the relationship between changes in nature exposure and well-being in the context of an individual's baseline nature affinity and subsequent feelings of nature deprivation at a time when most Americans were affected by stay-at-home restrictions.
Data were collected from a survey sample (N = 529) including respondents from 36 U.S. states, plus Puerto Rico and the District of Colombia. Thirty-six percent of respondents were from large urban or suburban areas. Participants were asked about availability of and exposure to nature during the pandemic lockdown. Information was collected on indoor exposures (e.g., window views and indoor plants), neighborhood exposures (e.g., local residential greenspace), and municipal sites (e.g., parks, conservation land, and beaches). Investigators also queried on degree of lockdown restrictions (varying by area).
Nature affinity was assessed by the Inclusion of Nature in Self scale measuring degree of connectedness with nature. Well-being was measured using the Harvard Flourishing Index. This measure includes five vital element domains: happiness and life satisfaction, mental and physical health, meaning and purpose, character and virtue, and close social relationships. A sixth domain, financial and material stability, was included given potential implications of COVID-19 wage or job loss on well-being. Nature deprivation was assessed through strength of agreement with this statement: “I feel nature deprived since coronavirus restrictions were imposed.”
The study found through multivariable regression that medium and high levels of baseline nature affinity strongly predicted higher perceived nature deprivation. Individuals with strong feelings of nature deprivation and withdrawal of opportunities to engage with nature under lockdown, in turn, had strongly diminished flourishing. Greater time spent in nature during the lockdown compared with prepandemic had the most significant effect on reducing feelings of deprivation. Public nature parks and reserves remaining fully open were associated with lower perceived nature deprivation. Analyses were controlled for degree of lockdown restrictions and sociodemographic variables (e.g., job status and household composition).
Interestingly, the actual contact with nature during this time varied across the sample (52% spent less time, 20% the same amount, and 38% spent more time compared with prepandemic). Authors speculate that these variations might have reflected a range of possible individual circumstances. For example, with the shift to virtual and decreased time spent commuting, some may have had more time and sought out nature in the relatively safer outdoors where fresh air and social distancing was more possible. Others may have had different work–life experiences or simply did not have access to such spaces. Of note, neighborhood-level nature contact was a major driver of cumulative nature exposure. This finding underscored the relevance of neighborhood greenspace to our health and well-being.
While this study is limited in interpretation due to its cross-sectional design, it does provide interesting snapshots. One important value of the study is in pointing out the important, yet often overlooked individual-level factors in understanding nature exposure and well-being. The degree of your inborn baseline nature affinity may dictate your perceived deficiency when deprived of nature. Evolutionarily we are still bound to nature, and this has important consequences on multiple domains of human flourishing in our modern day lives.
The study also highlights important public health implications. Widespread lockdown restrictions such as during the COVID pandemic unfortunately may become more common—not just for infectious disease-related threats, but climate exposures and other extreme environmental emergencies. How do we then reconcile this, protect our local natural resources, and leverage the natural world we yearn to stay connected with to guide us well beyond the current crisis? Now more than ever, it seems, mindful awareness toward our interdependence with the natural world might have a most direct and influential impact on our basic human flourishing.
Forest Bathing for Hypertension: A Fad or a Prescription?
Director of Education
Osher Center for Integrative Medicine
Harvard Medical School and Brigham and Women's Hospital
Medical Director, Benson-Henry Institute for Mind Body Medicine
Massachusetts General Hospital
ORCID ID (
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Studies have found changes in physiological measures such as blood pressure and heart rate, neurohormonal measures such as cortisol, and immunologic measures such as natural kill cell activity. In sum, there is a belief that forest bathing may have a therapeutic role, but the synthesis of evidence is limited at best. However, these analyses are necessary, especially to develop preventive strategies for conditions such as hypertension and its precursor, prehypertension.
One of the challenges of forest bathing—much similar to other mind–body therapies—is knowing the duration, type, and frequency of the interventions themselves. From the geography and topology of the site to the actual guided instructions provided to participants, to the length of session and number of sessions, there is significant variation as to what is being studied. In addition, this heterogeneity makes it difficult to understand its impact as a medical intervention in the management of prehypertension and hypertension. In this systematic review by Yau and Loke, they aimed to look at the benefits of forest bathing in this patient population; and they aimed to comment on what seems to be best type, frequency, and duration of the forest bathing intervention.
The authors followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and identified studies through systematic searches in PubMed, Cochrane Library, CINAHL, PsycInfo, and Chinese Academic Journals. Inclusion criteria were adults with prehypertension or hypertension, intervention study with forest bathing or forest environments, and reported psychological (i.e., mood) and physiological outcomes (i.e., blood pressure). Studies were excluded if they were cross-sectional or involved participants who were pregnant, had cancer, stroke, or mental illness. A total of 14 intervention studies were included in this systematic review (3 randomized controlled crossover trials, 4 randomized controlled trials with parallel groups, 1 nonrandomized controlled trial, 5 quasi-experimental studies, and 1 quasi-experimental comparative study).
The quality of the studies was assessed using the quality assessment tool for studies with diverse designs, and the study authors found that they were moderate to good in their evaluation (scores ranging from 23 to 31 out of 42). The 14 studies represented 951 participants (sample size range 9–290), with much greater representation of men; all studies included prehypertensive and hypertensive patients. Of note, more than half the studies were from Japan.
Four types of interventions were identified: forest walking (i.e., walking on paths in a forest), landscape viewing (i.e., being outside looking at a forest landscape), forest walking and viewing (combination of the two), and multimodal forest therapy program (i.e., stress management activity carried out in a forest). The authors provided narrative descriptions of multiple factors, including timing of the intervention, weather conditions, duration/frequency of intervention, presence of control/comparison group, and time points of outcome measures.
Physiological outcomes included blood pressure, pulse rate, heart rate variability, and cortisol levels, cardiac-pulmonary function, metabolic parameters, and cytokine levels. The psychological outcomes included mood state, anxiety level, and quality of life. Half of the studies had the duration of the intervention be between 45 and 90 min, and the majority were single session interventions. In addition, the majority did not have a control group, and most studies looked at physiological and psychological outcomes immediately before and after the intervention. Very few studies looked at the sustained effects of the intervention.
The authors reported that there might be benefits of forest bathing in reducing blood pressure (5%–15% reductions in systolic and diastolic blood pressure), reducing heart rate (3%–7% reductions), and increasing heart rate variability (10%–30% increases in the high-frequency component). In addition, most psychological metrics also improved after the intervention in the studies that examined them. Of the types of forest bathing, the authors suggested that forest walking and the multimodal forest therapy programs (which included other relaxation exercises) seemed to offer greater benefits around blood pressure. While the authors were encouraged, they noted higher quality studies were needed—with better descriptions of the intervention. And given that hypertension is a chronic illness, there needs to be a more thorough evaluation of sustained outcomes.
There are several aspects to this systematic review that are worth noting. First, it looked at non-English articles—in this case, specifically Chinese. So often, many reviews are limited to English only. Second, the authors were able to categorize the type of interventions. Research around forest bathing will require shared language in the description of the intervention. Third, this review provided important insights into how interventions need to be designed and outcomes need to be measured, especially for chronic medical conditions.
The authors identified multiple factors (e.g., weather conditions, duration, and timing) that can impact a forest bathing intervention. Despite this, for a quantitative measure such as blood pressure, rigorous meta-analyses and reviews would serve to better understand the magnitude of effects, as well as its clinical relevance. For Japan, forest bathing became part of a national public health initiative, and it has evolved into a whole world phenomenon. However, we are still left wondering what forest bathing means as a whole world prescription.