A prescription for “nature” – the potential of using virtual nature in therapeutics
Received 3 July 2018
Accepted for publication 20 September 2018
Published 8 November 2018 Volume 2018:14 Pages 3001—3013
Checked for plagiarism Yes
Review by Single-blind
Peer reviewers approved by Dr Justinn Cochran
Peer reviewer comments 2
Editor who approved publication: Dr Roger Pinder
Matthew P White,1 Nicola L Yeo,1 Peeter Vassiljev,2 Rikard Lundstedt,3 Mattias Wallergård,3 Maria Albin,4–6 Mare Lõhmus4–6
1The European Centre for Environment & Human Health, University of Exeter Medical School, Knowledge Spa, Royal Cornwall Hospital Treliske, Truro, Cornwall TR1 3HD, UK; 2Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, 51014 Tartu, Estonia; 3Department of Design Science, Division of Ergonomics and Aerosol Technology, Lund University, 22100 Lund, Sweden; 4Faculty of Medicine, Department of Laboratory Medicine, Division of Occupational and Environmental Medicine, Lund University, 22363 Lund, Sweden; 5Institute of Environmental Medicine, Karolinska Institute, 17177 Stockholm, Sweden; 6Centre for Occupational and Environmental Medicine, Stockholm County Council, 11365 Stockholm, Sweden
Abstract: Many studies suggest that increased exposure to urban greenness is associated with better population health. Accessing nature can in some circumstances, however, be difficult, especially for individuals with mobility constraints. Therefore, a growing body of work is investigating the ways to replace the in vivo experience with forms of “virtual” contact, in order to provide these individuals with at least some benefits of the natural environment. The aim of this paper is to provide a review of previous use of virtual reality (VR) nature in health and care settings and contemplate the potential use of this technology in future. Our central question is whether engaging with virtual nature can contribute to enhanced physical and emotional well-being in housebound or mobility-constrained individuals. We conclude that while contact with real-world nature is preferred, VR use can be an alternative in cases when in vivo contact with nature is not possible. There are many possibilities for the use of VR technology in psychiatric and medical care; however, the risks, benefits, and cost efficiency of these attempts should be carefully assessed and the outcomes should be measured in a scientifically valid manner. The current review has nonetheless demonstrated that VR nature could play a role in each of the proposed mediating mechanisms linking natural environments and health.
Keywords: virtual reality, green space, blue space, clinical use of VR, elderly care, mobility-constrained individuals, life quality, pain relief, life quality
A wealth of evidence now exists to suggest that even short-term exposure to natural settings such as woods, parks, and beaches can have a range of positive outcomes for health and well-being, especially among urban populations.1–7 Many international studies, including a report from the WHO,8 suggest that increased exposure to urban greenness (urban vegetation) is, for instance, associated with reduced general mortality, improved mental health, increased physical activity, and better birth outcomes.8–10 However, accessing nature can in some circumstances be time consuming and difficult, especially for individuals with mobility constraints, eg, physical disabilities or in care situations.9–13 Therefore, a growing body of work is investigating the ways to replace the in vivo experience with forms of “virtual” contact, in order to provide these individuals with at least some benefits of the natural environment.
In the current paper, we focus on both previous use of virtual reality (VR) nature in health and care settings and future potential use, in a rapidly growing technological field. Our central question is whether engaging with virtual nature can contribute to enhanced physical and emotional well-being in housebound or mobility-constrained individuals. We refer to urban vegetation as the “green structure” and to urban bodies of water as the “blue structure”.
The definition of VR is rather ambiguous. Often this term is simply used to refer to the physical equipment, ie, the hardware (eg, head-mounted displays [HMDs]), which enable viewing of virtual worlds. In this technological sense, VR has existed in one form or another since the 1950s and has been frequently used in space, flight, and military training and research. Commercially, however, this kind of technology has only recently become viable, through development of mobile, stand-alone HMDs such as Oculus Go (https://oculus.com/go) and high-end HMDs with so-called room-scale tracking and advanced hand controllers (such as the HTC VIVE, https://www.vive.com/eu/ and Oculus Rift, https://www.oculus.com/en-us/). Others define VR in terms of the virtual content, ie, the presentation format of the virtual worlds. Most often, this entails a computer-generated three-dimensional (3D) environment that permits some level of user immersion and interactivity (sometimes referred to as “true VR”). VR in the present review refers to an interaction between a person and a computer-based environment, including different set-ups such as nonimmersive flat screens, semi-immersive exposures consisting of picture projection on walls/floors, and immersive experiences through HMD.
VR in psychiatry and medicine today
Since the 1990s, the potential of using different types of VR devices in prevention and treatment of both mental and physiological health problems has been of increasing interest.14 Generally, studies show that the use of VR technology in medicine is both easy and safe and results in high patient satisfaction.14 Examples of present therapeutic applications of VR devices are briefly reviewed below with specific attention to cases where virtual natural landscapes have been used. However, as far we are aware, only two existing studies15,16 have compared the exposure effect of virtual nature views to the effect of any other type of virtual view, which makes it difficult to conclude whether the observed effects depend on the exposure to VR nature per se or if they are created by a simple distraction effect of an VR experience.
Virtual reality in pain management
Alleviation of the sensation of pain is probably the most thoroughly investigated area concerning the possibilities of using VR techniques in therapeutics. Accurate pain management is of great importance and prevents several long-lasting consequences associated with adverse physical and psychological sequelae.17–19 In pharmacological treatment, severe pain is typically managed by blocking sensory information via opioid analgesics. Opioids, however, have several negative side effects including nausea, constipation, immunosuppression, and respiratory and cognitive implications.19 Furthermore, there is a risk of increased tolerance and a need for higher doses with chronic use, as well as a risk of developing a psychophysiological drug dependence.14,20,21 Thus, VR devices have been presented as a noninvasive alternative, with minimal (known) side effects.
When discussing the applicability of using VR in pain management, it is important to differentiate between acute and chronic pain, as the physiological mechanisms leading to these two types of pain sensations can be quite different. While acute pain is caused by a demonstrable tissue injury and is associated with increased activity in a set of brain structures referred to as the “pain network”, chronic pain may not be a symptom of an observable injury or disease at all. More usually, chronic pain is regarded as a disease entity in its own right and involves activity changes in very different neural circuits than acute pain.22
Most VR approaches used in attempts of acute pain alleviation involve some type of immersive game. The underlying principle of these games is that attention is diverted away from the painful stimulus through immersion in virtual action, so called “distraction therapy”.23 Examples include the SnowWorld VR system (HITLab, New York, NY, USA), RelieVR (AppliedVR™, Los Angeles, CA, USA), and the Bear Blast (AppliedVR), which have been used effectively during wound care in patients with burn injuries and other kinds of painful treatments in bedbound adults and/or children.14,20,21,23–26
Only a couple of studies have tested the possibility of providing distraction from an acute painful procedure by exposure to VR nature in particular. Tanja-Dijkstra et al reported an alleviating effect on pain experience and pain recollection in dental patients who were exposed to virtual coastal views but not in those exposed to virtual urban environments, compared to standard care controls.15 However, as patients were also treated with local anesthetics, the effect of the VR nature exposure may be rather due to the reduction of anxiety and expectations of pain, than of the pain sensation per se. An earlier study by Tanja-Dijkstra et al showed that letting the participants of a simulated dental procedure experience a VR coastal walk resulted in reduced anxiety and vividness of memories when compared to the individuals who were not exposed to VR.27
In chronic pain management, using VR technology, depicting nature has shown promising results, especially when combined with various psychotherapeutic approaches. A study by Patterson et al19 combined visual VR treatment with hypnotic suggestions in hospitalized trauma patients. Through a HMD, the patients were first exposed to views of an icy canyon, starry skies, and a gently flowing river and continued thereafter their virtual flight into a lush valley with a lake. Adding this combination of VR/hypnosis treatment to the standard analgesic care resulted in reduced subjective pain at both 1 and 8 hours posttreatment compared to standard care alone, although it is unclear what role VR nature played over and above the hypnosis element. Gromala et al28 combined virtual forest walks with mindfulness meditation in chronic pain patients and found that the combination of VR and mindfulness-based stress reduction training was more effective at reducing perceived pain than the mindfulness training alone. A combination of mindfulness meditation, education in pain management, and usage of VR devices depicting either beach or meadow scenarios (including the natural sounds), has also shown long-term benefits in form of significantly reduced pain and depression in fibromyalgia patients.29
Neurological disorders and stroke rehabilitation
Everyday activities demand certain aspects of body functioning. Unfortunately, many neurological disorders (eg, Parkinson’s disease, cerebral palsy) or life events (eg, strokes, traumas) can decrease individuals’ mobility, resulting in reductions to life satisfaction and well-being.30 Consequently, rehabilitation programs that increase individuals’ physical abilities have been of great interest. VR rehabilitation programs (most of which have been nonimmersive, but there are exceptions) have focused on four primary outcomes: motor control,31–36 balance,37–41 gait,42–46 and strength. A recent meta-analysis concluded that, in general, these programs constitute an efficient form of therapy, which is occasionally more effective than the comparable standard rehabilitation programs.30 One reason for the success of VR treatments may be that the traditional rehabilitation programs often involve repetitively performing “movements without purpose” while the VR environments may provide the patients with more stimulating and motivating tasks. Most of these VR approaches also include a “feedback moment” that is achieved by recording the movements of the patient during the VR exposure and directly projecting these movements into the VR world, which in turn allows the patient to immediately adjust their motions. The effect of natural environments as such has not been a focus in any VR rehabilitation studies that we have come across. However, in some cases, elements of nature or nature views have been used as a background to an interactive game.31,40,43 One approach of VR rehabilitation of children with neurological gait disease has included a navigation game depicting a walk in virtual nature.43 Furthermore, rehabilitation treatments combining walking on a real-world treadmill with, for example, trying to avoid collision with virtual objects41,45,46 have in some cases41 depicted walking in a natural landscape.
Virtual reality as a distraction and relaxation tool in cancer treatment
Cancer treatment involves a wide variety of physically and emotionally depleting procedures, such as chemotherapy, painful invasive procedures, and hospitalization.47 Oyama et al48 published the first study on the topic and demonstrated that viewing beautiful scenery with nature sounds and scents significantly decreased negative emotions, pain, and anxiety in patients during ongoing chemotherapy infusion. Several later studies that have used VR technology in order to relieve chemotherapy-related distress symptoms (ie, either ocean or art views) indicated reduction in anxiety, distress and fatigue (see Chirico et al47 for review) and perception of shorter treatment time in patients using VR compared to the ones who did not.
Exposure to VR nature has also been used in attempts to reduce the distress of hospitalization in cancer patients. Baños et al51 investigated the effect of an intervention that consisted of four 30-minute sessions during 1 week in which cancer patients navigated through virtual environments, such as an urban park or a wild forest. Although an increase in positive emotions was detected in VR-treated patients, the authors also noted some difficulties with using the VR devices, potentially limiting the technology’s feasibility. A similar experimental design was used by Espinoza et al,52 who reported that exposure to the VR intervention resulted in reduction of stress and significant improvements in levels of happiness in hospitalized cancer patients.
Mental health and well-being
The use of VR therapies for mental health and well-being has focused mainly on treatment of anxiety disorders, eating disorders, phobias, and post-traumatic stress disorder. According to a recent systematic review by Valmaggia et al,53 studies published pre-2012 generally showed that VR was an effective form of therapy for mental disorders compared to “treatment as usual”; however, generally, their effect was either equal or less efficient than conventional cognitive behavior therapy (CBT).53 Studies published after 2012 provide evidence for VR being more effective than “treatment as usual” and also indicated that VR can be as effective as or in some case even more effective than CBT. This may reflect improvements in the immersiveness of the experiences achieved through technological advances over this period.
Eating disorders and obesity
Eating disorders are widespread and often chronic mental disorders. Use of VR treatment in eating-disorder patients has typically involved exposure to food items in virtual supermarkets or kitchens, where the patients are encouraged to reflect over food cravings and to make healthy food choices; alternatively, these provide training for improved body image through repeated exposure to diverse body types.54–60 This kind of VR treatment is typically combined with other psychological therapies, teaching coping skills in the real world. The results generally show that using VR devices improves the capacity of obesity patients to maintain long-term weight loss.
To the best of our knowledge, only one of the eating-disorder studies has used VR nature imaging as a form of therapy. In this study a relaxation therapy, provided by a trained psychologist, was used either alone or in combination with VR nature images in individuals belonging to a weight-loss program.61 At 3-month follow-up, the patients using VR in combination with relaxation therapy were found to be better at reducing emotional eating than the ones who were exposed to the psychologist-provided therapy only.
Phobias, anxiety, and agitation
Phobias and social anxiety disorders significantly affect quality of life and hinder various everyday and/or recreational activities. In studies attempting phobia treatment through VR devices, patients are typically introduced to virtual objects, conditions, or environments containing the person-specific type of fear (ie, spiders, crowds, heights, needles, listening audience) gradually over the course of repeated sessions over several weeks, in a process known as systematic desensitization.62–70 In general, the combined data from these studies are promising and encourage continued development of VR in treatment of phobias and social anxiety, especially in cases where in vivo treatment may not be safe or feasible.68
Post-traumatic stress disorder entails past involvement in a traumatic event, and symptoms, such as intrusion, avoidance, negative alternations in cognition and mood, and/or changes in arousal and activity.68 The VR therapy of this disorder has involved, for example, exposing patients to an environment with sounds and images similar to the site of the past traumatic event.70–72 The practicality of this approach is obvious as recreating certain environments in vivo may, in many cases, be both undesirable and physically impossible. Results suggest that VR treatments in this field show robust improvements (with medium to large effect sizes) in key outcomes compared to standard exposure treatments.68 Natural landscapes and natural sounds have been used in specific cases, involving for example rehabilitation of the veterans of Vietnam war, where the images (viewed from a helicopter) of the Vietnamese jungle were used, although clearly in this case, the natural scenes were not necessarily intended to be calming and restorative in the way in which many other VR nature interventions often aim to be.72
A slightly different form of anxiety relates to the agitation experienced by many people with dementia, a state that imposes large burdens of care on caregivers. Reynolds et al16 compared the effect of VR nature (nonimmersive, in this case) to one of VR with other content (a generation movie in this particular case) and found that heart rate declined significantly when the patients were exposed to virtual nature compared to the control group. A trend toward happier emotional states during VR nature exposure was also observed.16
Although anxiety and depression have different etiologies and symptoms, co-occurrence is common73,74 and the initial medical treatment of these disorders is often very similar. Thus, we might expect a similar number of studies exploring the use of VR in the treatment of depression. To date, however, there have been far fewer VR studies looking at depression than anxiety-related issues and the few examples that do exist have all chosen very different approaches. VR devices have been used, for example, to present an educational video of different relaxation techniques,75 to enable patients to practice delivering and receiving compassion through a virtual body,76,77 or to train people with depression to cope with everyday situations.78 Despite epidemiological evidence and controlled field studies that suggest that greater exposure to natural settings can reduce the risk and help in the treatment of depression,3,79 we found that no studies attempted to investigate the effects of exposure to virtual nature in depressed individuals.
The greater number of studies looking at the use of VR to support the treatment of anxiety-related disorders compared to depression is intriguing but perhaps not surprising. Anxieties are often related to specific targets or triggers (eg, snakes, memories of trauma, situational uncertainty), which may be impossible or unsafe to recreate in “real” treatment situations but have the potential to be tackled individually and “synthetically” and “safely” with the use of targeted VR treatments. Depression, by contrast, is often a more diffuse condition characterized by a general lack of interest in daily activities and lower energy levels and feelings of self-worth, which are less obviously tackled with specific VR interventions.80 Moreover, depression may also be accompanied with greater apathy and reluctance to try new things, making it difficult to engage people with innovative treatments such as VR. These thoughts are largely conjecture at this stage, and further research is needed to tease apart if and why VR may be more productive in the treatment of anxiety than depression-related issues.
Cognition refers to the mental processes associated with processing information and responding with appropriate actions.81 Cognitive impairment is a common effect of neurodegenerative diseases, traumatic brain injuries, and stroke and can lead to reduced ability to perform self-care tasks and participate in social and community activities. Different multistimuli therapeutic VR systems, for example, BTS-Nirvana82 and VRROOM83 have been tested in attempts to provide relaxation, or as tools for attention and memory training in traumatic brain injury and stroke patients.82,83 Depending on the aim of the rehabilitation and of the target group, the VR approaches may include, for example, views of a natural marine environment,82 or a 3D city (NeuroRehabLab, Madeira Interactive Technologies Institute, Funchal, Portugal) where the patients will be able to train how to accomplish specific everyday tasks.84 Generally, VR is considered to be a new, useful, and cost-effective tool for cognitive rehabilitation;85 however, more research is needed to identify the patient and treatment factors that contribute to successful outcomes.
Present development of VR technology
Presently, VR technology is developing at an unprecedented speed and transforming from a “hyped, overrated technology” to a commercial reality.86 Still, VR has some way to go before it can be considered as a “mainstream technology”, comparable to the user friendliness of laptops and smartphones. Current commercial VR systems, such as the HTC VIVE and Oculus Rift, are still relatively expensive and require a high level of computer proficiency, which reduces accessibility for most people.
Today, features such as increased resolution, larger field of view, wireless data transmission, and more possibilities for interaction are the main areas for the development of the major VR producers. In addition, the social dimension of VR, which presently is relatively underdeveloped, is expected to gain more importance in the future. Companies, such as Facebook and Sansar, are investing a lot of effort into bringing a social dimension to their virtual worlds.
Developing realistic VR nature has been, and still is, especially challenging. Due to the complexity and variety of the natural environments, many attempts to depict virtual nature have resulted in static, flat, and artificial impressions. Trees, for example, have often been modeled as a collection of texturized planes, and it has been even harder to mimic the appearance and behavior of water environments, attempts of which have often resulted in “plastic” and lifeless images. However, greater accessibility to open-source data, courtesy of major VR software developers (eg, Unreal Engine 4, https://www.unrealengine.com/en-US/what-is-unreal-engine-4), provides new opportunities for building realistic VR nature applications.
Taking a longer perspective, VR systems will most likely not be limited to visual and auditory stimuli. For example, Long et al87 have demonstrated that it is possible to render volumetric haptic shapes in mid-air using ultrasound. Integrating this technology in VR technology would make it possible to not only see a virtual ball but also to touch it, even without using a haptic-enabled device (such as haptic gloves). Furthermore, developers are working on olfactory displays, which make smelling a virtual flower possible. However, many technological hurdles need to be overcome before this technology finds its way into consumers’ hands.
Pathways linking health with nature exposure and the applicability of these in VR-based therapies
There are now numerous empirical studies1–7 supporting the contention that expose to natural environments may be beneficial for human health. In the following sections, we consider the underlying mechanisms behind any possible benefits so that VR designers can begin to incorporate them in their designs in order to help optimize the experience and outcomes for patients.
The WHO’s 20168 report “Urban green spaces and health: A review of evidence” suggested nine possible pathways linking the observed health outcomes and urban green and blue infrastructure (ie, urban nature). These included:
- Improved relaxation and restoration
- Improved social capital
- Improved functioning of the immune system
- Enhanced physical activity, improved fitness, and reduced obesity
- Anthropogenic noise buffering and production of natural sounds
- Reduced exposure to air pollution
- Reduction of the urban heat island effect
- Enhanced pro-environmental behavior
- Optimized exposure to sunlight and improved sleep.
Below, these mechanisms are briefly discussed from the viewpoint of possibilities for using VR nature as a tool to promote positive outcomes in different groups of patients.
Relaxation and restoration
Green and blue environments are suggested to have a relaxing effect, allowing people to recover from demanding situations.8 It is plausible that green space affects the brain and body via psychoendocrine mechanisms, including the function of the hypothalamic pituitary adrenal (HPA) axis. The HPA axis regulates stress hormone (cortisol) secretion, and its dysregulation is associated with a wide range of disease outcomes and immune system malfunction.88 Several studies have provided evidence for this theory;89 however, the complexity and sensitivity of the stress regulation physiology are often a methodological complication.
One pilot study has been conducted to investigate the effect of VR nature (with and without nature sounds) on physiological stress recovery in healthy volunteers.90 During this experiment, the virtual environment was presented by using a CAVE™ system (EON Development Inc., Gothenburg, Sweden) including three rear-projected walls and a floor projection. The results were promising, indicating enhanced stress recovery and parasympathetic activation in the group exposed to the VR nature including sounds, compared with the individuals exposed to the VR nature without sounds, or controls who got to read a popular science magazine. Interestingly, the authors reported that being exposed to a silent virtual forest (in contrast to the virtual forest with natural sounds) occasionally was perceived as a bit uncanny by the participants. This indicates that for being able to provide a coherent “nature-like experience” combining multiple sensory (eg, visual and auditory) cues may be important.
VR interventions depicting rich natural environments with multisensory stimuli may thus have a potential for use in a range of medical, psychiatric, and possibly even in palliative care contexts, as a means for recovery from or reduction of stress and anxiety in individuals who are either bedbound or experience reduced mobility. Stroke, cancer patients, and the elderly might be examples of groups, in particular, where VR nature exposure could be used for increased mental well-being. Since decreased rumination and increasing meditation may be an effect of exposure to nature environments,91,92 VR nature treatment may also be beneficial for the reduction of depressive symptoms, associated with, for example, long-term illness, chronic pain, or hospitalization.
Improved social capital
Social relationships have a well-known protective health effect.93,94 Social isolation on the other hand is a predictor of morbidity and mortality.95,96 Both the quantity and quality of green and blue space have been suggested to foster social interactions and promote a sense of community, among adults and children,97–100 whereas a shortage of green space in the residential environment is associated with feeling lonely and lacking social support.101,102
On the face of it, improved social capital as a mechanistic pathway linking health and green and blue structure does not sound particularly relevant when discussing the possible use of VR nature in therapeutics. However, providing individuals with limited mobility with easily used technology that allows experiencing virtual nature walks or ocean explorations in combination with virtual (eg, online) meetings with friends or family members (using VR devices, as well) is an interesting possibility. Previous studies have shown that increasing the computer skills in the elderly and introducing social networking and videoconferences in care homes can reduce the level of loneliness in the elderly.103–105 Adding a component of a virtual world where the elderly can “walk” together with friends or relatives and share their observations and experiences while “walking” may thus increase the perception of quality of life. Loneliness is a common problem in older adults, in particular, and strongly associated with the risk of different health problems and decreased functional capability.106,107 Chronic pain and long-term illness, on the other hand, increase the risk for loneliness.108,109 Combining virtual social interaction with the relaxation effect of VR nature could thus contribute to both avoiding feeling lonely and to decreasing the risk for illnesses associated with loneliness.
Improved functioning of the immune system
Enhanced immune functioning has been suggested to be a central pathway between nature and health.110 However, as far as we are aware, no cohort/population studies exists that link the urban green or blue structure to improved the immune system. Thus, this hypothesis is mainly based on publications that are, for example, reporting the immune system-stimulating effects of Japanese “forest bathing” tradition111 as well as on studies indicating that increased exposure to biodiversity, natural allergens, and diverse microorganisms in natural environments is associated with beneficial health outcomes.112,113
For obvious reasons, VR will not be able to copy the microbial or biochemical effects of in vivo nature. On the contrary, using VR devices in hospitals, for example, would expose the users to a “clean nature”, while the presence of indoor plants may entail some exposure to allergens and microorganisms. Thus, the only way we can see of VR nature affecting the immune system would be through the previously described pathway of relaxation/stress reduction.
When discussing stress, it is important to differ between the physiological pathways activated during acute vs chronic exposure. While acute stress is a fundamental and adaptive survival mechanism, that is generally without long-lasting effects on the immune system, then long-term, chronic stress suppresses and dysregulates both innate and adaptive immune response.114,115 Consequently, chronic stress is also likely to increase susceptibility to a large number of diseases. Thus, exposure to VR nature may, by inducing relaxation and thereby reducing the immune deleterious effects of chronic stress, improve the functioning of the immune system and physical recovery in hospitalized patients or in individuals suffering with long-term illness.
Enhanced physical activity, improved fitness, and reduced obesity
One of the most often mentioned behavioral pathways linking green and blue structure and health is the motivation for physical activity. Abundant vegetation and bodies of water provide an inviting setting for physical activity, which has a well-established positive impact on both physical and mental health.8 Studies conducted in different parts of the world have reported that recreational walking, increased physical activity, and reduced sedentary time are associated with the use of and access to green and blue space,9,116–124 particularly among certain groups such as dog owners.125
Public use of VR devices is more often associated with physical inactivity than activity. Using VR in medical care should, therefore, be recommended primarily for the treatment of patients with reduced mobility or in cases when in vivo nature exposure is not possible. However, as described above, a number of motor rehabilitation studies have found that using VR technology increases the enthusiasm and motivation of the patients for rehabilitation training compared with traditional physiotherapy. Thus, motor rehabilitation exercises enabling virtual walking, swimming, or paddling in natural landscapes may provide a more motivating training environment and combine the positive health effects of both physiotherapy and green and blue structure.
Reduced exposure to harmful environmental exposures
Urbanization increases citizen’s exposure to noise and air pollution as well as the urban heat island effect.126 Although urban nature can mitigate some of these effects, it rarely eliminates them. Thus for particularly vulnerable individuals (eg, people with COPD or elderly), it may be better to recommend virtual contact with nature than actual contact with (urban) nature when conditions are poor (eg, high temperatures and high noise or air pollution levels).
Enhanced pro-environmental behavior
Pro-environmental behavior entails “behavior that consciously seeks to minimize the negative impact of one’s actions on the natural and built world”.8,127 It has been suggested that external stimuli, in the form of exposure to natural environments, especially during childhood, may be important to induce pro-environmental behavior.128,129 The beneficial health effect of this pathway is suggested to be achieved by increasing people’s motivation to create (and give rise to) a less polluted outdoor environment.
It is possible that being exposed to virtual nature can modify people’s attitude and interest for environmental thinking.130 A key concern in recommending the use of VR devices for a “nature experience” is that it might increase the likelihood for stationary lifestyle and decrease individual’s motivation to in vivo nature exposure. However, in some groups of patients, such as the sufferers of specific anxieties and phobias (ie, water, fish, insects, and many more) or of depression-related apathy,131 exposure to VR nature might provide the kind of external stimuli needed to trigger an appreciation and interest for in vivo nature exposure.
Optimized exposure to sunlight and improved sleep
If access to green and blue structure is associated with more time spent outdoors, it is also likely to be accompanied by increased exposure to sunlight. Exposure to sunlight is crucial for vitamin D production in human, and optimum levels of vitamin D are important for a multitude of physiological functions contributing to health and well-being. Increasing the time spent on outdoor activities significantly decreases the risk for vitamin D deficiency.132,133 Furthermore, exposure to ultraviolet (UV) light has often been associated with negative health effects; however, a recent study has indicated that UV-induced release of nitric oxide in the skin might contribute to better health by lowering the risk of hypertension and cardiovascular disease.134 Exposure to daylight, in general, stimulates alertness, controls circadian rhythms, and promotes healthy sleep. Adequate sleep is crucial for good health, and sleep deprivation has been linked to many adverse health effects.135–137 Several studies suggest that living in a greener neighborhood lowers the risk for insufficient sleep.8,138,139 It is possible that increased greenness increases people’s exposure to natural daylight and in this way helps to maintain circadian rhythms.
VR is not likely to become a replacement for sunlight exposure, although it could be used in conjunction with sunlamps, which have been demonstrated to help combat mood disorders among individuals who get little direct sunlight (eg, in winter).140 However, by increasing the interest in or decreasing the fear of experiencing nature in vivo (as described in the section above), it may in some cases result in increased interest in spending time outdoors. In northern latitudes, the usage of light therapy devices or light rooms is increasing in popularity during periods of cold weather and short days. Combining light therapy with exposure to virtual nature could provide additional health benefits.
Challenges and considerations for using VR in clinical or care home settings
Besides opportunities, use of VR technology also involves certain challenges and risks. The feasibility and cost efficiency of using VR technology instead of classical treatment methods may be more suitable in some groups of patients than in others and needs careful evaluation.141,142
The mental and physical capability of the user is important to be taken into account when the use of VR devices is considered. Cybersickness is the most often mentioned complication associated with the use of HMD VR devices. As HMDs, at least partly, eliminate visual cues from real world and involve high level of stereoscopic and stereophonic immersion in virtual world, this can give rise to a mismatch between visual and vestibular systems and occasionally trigger cybersickness.143 Old age and certain neurodegenerative diseases have been occasionally observed to hamper the ability to use HMDs in physical training.144 For example, older individuals have been observed to have more difficulties to readjust their posture145 and walking direction145,146 while using HMD compared with younger ones. Older people also experience greater difficulties when exposed to incorrect or mismatched visual, somatosensory, and vestibular information than younger individuals do.147 Thus, it has been suggested that integration of visual and vestibular sensory information should be specially designed for use by older people.148 The new generation of HDMs, such as the HTC VIVE, may eliminate some of the risks for sensory mismatch thanks to their tracking system, which allows the generated real-time 3D view to be updated according to the user’s orientation and movements.149 Other simulator display technologies (such as spherical and angled 3-panel) that induce vection150 (ie, illusions of self-motion) and, thus, a heightened degree of immersion, have been suggested as an alternative to HMDs. However, the risk of simulator sickness in older people has also been reported with angled 3-panel driving simulator.151
Scientific reports generally concentrate on reporting results provided by individuals participating in the studies. However, to be able to learn from past experiences, we may occasionally benefit from learning about patients who for different reasons were not able to participate. For example, when Mosadeghi et al152 investigated the applicability of HMD in hospital setting, 57 out of 87 eligible patients declined to take part in the experiment. Two participants reported symptoms of cybersickness and one additional dropout was due to frailty to support the weight of the device. Old age was, in this particular case, the only statistically differentiating factor characterizing the refusers. Other reasons for refusal included:
not understanding the purpose of VR, feeling anxious about using the goggles, feeling too tired or too ill to participate, concerns about “losing control” of one’s personal environment at a time when control is already limited, and harboring concerns that VR is a “psychological experiment”.152
Potential issues and fears like fitting corrective eyeglasses inside HMD, clumsiness of the wired apparatus, and limited extent of the VR content have also been reported in another study.153 Thus, in order to create a successful intervention, the need for proper training of both the users and the assisting staff should not be neglected.89 Dockx et al154 reported that initially less enthusiastic attitudes of older participants toward the use of VR in fall prevention training improved considerably after VR experience. A gradual introduction to VR by using television screens or angled 3-panel setups could be a solution to reduce feelings of fear among the potential patients. Perceived and actual abilities to stop and customize the content of the VR experience by the users have been reported as factors making the study environment more friendly and nonpushy.153 In addition to caretakers, care-providers will need support and training before VR interventions are introduced. Frequent use of VR technology in care homes is today largely hindered by the complexity of the technology and its maintenance. Thus, improvements in both design (in form of increased robustness and simplicity) and support packages, assisting with staff training, are necessary before VR technology can be routinely used in care facilities.
Finally, being a relatively new technology, there is currently a lack of longitudinal VR studies in clinical settings. Thus, there are research gaps to be addressed, both in terms of whether beneficial effects of virtual nature can be sustained with repeated exposure and whether there are any associated long-term adverse effects.
Other potential drawbacks of long-term VR use – addiction and mood changes
Due to the relatively recent emergence of consumer VR, the number of studies exploring long-term negative health or behavioral impacts of VR in humans is very limited. Thus, no studies to date have explored potential overuse and addictiveness of VR, and controversially, VR is, in fact, currently being utilized as a clinical tool to treat addiction.155,156
According to the researchers working in the field of human–computer interactions, until recently VR systems have presented too many short-term adverse effects to allow for long spells of immersion.157,158 Thus, it is conceivable that VR addiction among general public is going to increase following recent development of VR versions of popular console games that are designed to encourage long periods of uninterrupted gameplay. However, it is difficult to imagine that VR nature programs would promote overuse of the technology, in the way that gamified experiences might. Nevertheless, implementation of long-term VR nature use in clinical and care settings still requires a cautious approach, as some effects of it may be rather unexpected. For example, it is possible that VR nature experiences lead to lowered mood if users, especially those with health conditions that limit traveling opportunities, reflect that they may never be able to visit the depicted environments in vivo.
No studies to date have investigated what constitutes the optimal “dose” of the VR nature exposure. Positive health impacts of VR nature exposure in lab settings have been observed following both 5- and 15-minute treatment periods.90,159,160 Although these exposure times were intentionally selected to avoid potential adverse effects of VR HMDs (eg, cybersickness, eyestrain), some evidence suggests that short periods of nature exposure may be most beneficial for health. For example, Barton and Pretty 161 reported that 5-minute bursts of exposure to real natural environments were most beneficial for improving mood and self-esteem, irrespective of age, gender, location, and health status. Another study162 found that recovery from stress, in terms of pulse rate, skin conductance, and muscle tension, occurred much more rapidly in the first 4 minutes of exposure to nature photographs than at subsequent time intervals. According to a recent publication,163 viewing a virtual forest on a TV screen for just 90 seconds was sufficient to significantly reduce oxyhemoglobin concentrations in the right prefrontal cortex (indicative of physiological relaxation) compared to exposure to a virtual city. Thus, though to our knowledge, no studies have yet compared the relative effects of different VR nature exposure durations, short-term exposures may in fact prove optimal for well-being.
While contact with real-world nature is, in many cases, preferred and recommended, VR use can be an alternative in cases when in vivo contact with nature is not possible or not recommended for various reasons (eg, individual frailty, excess temperatures). There are many possibilities for use of VR technology in psychiatric and medical care; however, the risks, benefits, and cost efficiency of these attempts should be carefully assessed and the outcomes should be measured in a scientifically valid manner. The current review has nonetheless demonstrated that VR nature could play a role in each of the proposed mediating mechanisms linking natural environments and health, as proposed by the WHO, suggesting it needs not just be considered as a “nice to have gimmick”. Since this technology is changing and developing constantly, we can expect more technically advanced and fine-tuned VR approaches in the future.
We acknowledge the support of the H2020 EU project BlueHealth – grant agreement no. 666773.
The authors report no conflicts of interest in this work.
Bratman GN, Hamilton JP, Daily GC. The impacts of nature experience on human cognitive function and mental health. Ann N Y Acad Sci. 2012;1249(1):118–136.
Capaldi CA, Dopko RL, Zelenski JM. The relationship between nature connectedness and happiness: a meta-analysis. Front Psychol. 2014;5:976.
Gascon M, Triguero-Mas M, Martínez D, et al. Mental health benefits of long-term exposure to residential green and blue spaces: a systematic review. Int J Environ Res Public Health. 2015;12(4):4354–4379.
Hartig T, Mitchell R, de Vries S, Frumkin H. Nature and health. Annu Rev Public Health. 2014;35(1):207–228.
Keniger LE, Gaston KJ, Irvine KN, Fuller RA. What are the benefits of interacting with nature? Int J Environ Res Public Health. 2013;10(3):913–935.
McMahan EA, Estes D. The effect of contact with natural environments on positive and negative affect: a meta-analysis. J Posit Psychol. 2015;10(6):507–519.
Sandifer PA, Sutton-Grier AE, Ward BP. Exploring connections among nature, biodiversity, ecosystem services, and human health and well-being: opportunities to enhance health and biodiversity conservation. Ecosyst Serv. 2015;12:1–15.
World Health Organization. Urban Green Spaces and Health. A Review of Evidence. Copenhagen: WHO Regional office for Europe; 2016. Available from: http://www.euro.who.int/__data/assets/pdf_file/0005/321971/Urban-green-spaces-and-health-review-evidence.pdf?ua=1 World Health Organization 2016. Accessed October 29, 2018.
Fong KC, Hart JE, James P. A review of epidemiologic studies on greenness and health: updated literature through 2017. Curr Environ Health Rep. 2018;5(1):77–87.
Kondo MC, Fluehr JM, McKeon T, Branas CC. Urban green space and its impact on human health. Int J Environ Res Public Health. 2018;15(3):445.
Dallimer M, Davies ZG, Irvine KN, et al. What personal and environmental factors determine frequency of urban greenspace use? Int J Environ Res Public Health. 2014;11(8):7977–7992.
Hitchings R. Studying the preoccupations that prevent people from going into green space. Landsc Urban Plan. 2013;118:98–102.
Boyd F, White MP, Bell S, Burt J. Who doesn’t visit natural environments for recreation and why: a population representative analysis of spatial, individual and temporal factors among adults in England. Landsc Urban Plan. In press 2018.
Dascal J, Reid M, Ishak WW, et al. Virtual reality and medical inpatients: a systematic review of randomized, controlled trials. Innov Clin Neurosci. 2017;14(1–2):14.
Tanja-Dijkstra K, Pahl S, White MP, et al. The soothing sea: a virtual coastal walk can reduce experienced and recollected pain. Environ Behav. 2018;50(6):599–625.
Reynolds L, Rodiek S, Lininger M, Mcculley MA. Can a virtual nature experience reduce anxiety and agitation in people with dementia? J Hous Elderly. 2018;32(2):176–193.
Burke AL, Mathias JL, Denson LA. Psychological functioning of people living with chronic pain: a meta-analytic review. Br J Clin Psychol. 2015;54(3):345–360.
Outcalt SD, Kroenke K, Krebs EE, et al. Chronic pain and comorbid mental health conditions: independent associations of posttraumatic stress disorder and depression with pain, disability, and quality of life. J Behav Med. 2015;38(3):535–543.
Patterson DR, Jensen MP, Wiechman SA, Sharar SR. Virtual reality hypnosis for pain associated with recovery from physical trauma. Int J Clin Exp Hypn. 2010;58(3):288–300.
McSherry T, Atterbury M, Gartner S, Helmold E, Searles DM, Schulman C. Randomized, crossover study of immersive virtual reality to decrease opioid use during painful wound care procedures in adults. J Burn Care Res. 2018;39(2):278–285.
Maani CV, Hoffman HG, Morrow M, et al. Virtual reality pain control during burn wound debridement of combat-related burn injuries using robot-like arm mounted VR goggles. J Trauma. 2011;71(1 Suppl):S125–S130.
Henderson LA, Di Pietro F. How do neuroanatomical changes in individuals with chronic pain result in the constant perception of pain? Pain Manag. 2016;6(2):147–159.
Gold JI, Mahrer NE. Is virtual reality ready for prime time in the medical space? A randomized control trial of pediatric virtual reality for acute procedural pain management. J Pediatr Psychol. 2018;43(3):266–275.
Hoffman HG, Patterson DR, Seibel E, Soltani M, Jewett-Leahy L, Sharar SR. Virtual reality pain control during burn wound debridement in the hydrotank. Clin J Pain. 2008;24(4):299–304.
van Twillert B, Bremer M, Faber AW. Computer-generated virtual reality to control pain and anxiety in pediatric and adult burn patients during wound dressing changes. J Burn Care Res. 2007;28(5):694–702.
Tashjian VC, Mosadeghi S, Howard AR, et al. Virtual reality for management of pain in hospitalized patients: results of a controlled trial. JMIR Ment Health. 2017;4(1):e9.
Tanja-Dijkstra K, Pahl S, White MP, et al. Improving dental experiences by using virtual reality distraction: a simulation study. PLoS One. 2014;9(3):e91276.
Gromala D, Tong X, Choo A, Karamnejad M, Shaw CD. The virtual meditative walk: virtual reality therapy for chronic pain management. Poster presented at: Proceedings of the 33rd Annual ACM Conference on Human Factors in Computing Systems; April 18–23; 2015; Seoul, Korea.
Botella C, Garcia-Palacios A, Vizcaíno Y, Herrero R, Baños RM, Belmonte MA. Virtual reality in the treatment of fibromyalgia: a pilot study. Cyberpsychol Behav Soc Netw. 2013;16(3):215–223.
Howard MC. A meta-analysis and systematic literature review of virtual reality rehabilitation programs. Comput Human Behav. 2017;70:317–327.
Bermúdez i, Badia S, García Morgade A, Samaha H, Verschure PF. Using a hybrid brain computer interface and virtual reality system to monitor and promote cortical reorganization through motor activity and motor imagery training. IEEE Trans Neural Syst Rehabil Eng. 2013;21(2):174–181.
Broeren J, Rydmark M, Sunnerhagen KS. Virtual reality and haptics as a training device for movement rehabilitation after stroke: a single-case study. Arch Phys Med Rehabil. 2004;85(8):1247–1250.
Broeren J, Claesson L, Goude D, Rydmark M, Sunnerhagen KS. Virtual rehabilitation in an activity centre for community-dwelling persons with stroke. Cerebrovasc Dis. 2008;26(3):289–296.
Bryanton C, Bossé J, Brien M, McLean J, McCormick A, Sveistrup H. Feasibility, motivation, and selective motor control: virtual reality compared to conventional home exercise in children with cerebral palsy. Cyberpsychol Behav. 2006;9(2):123–128.
Kwon JS, Park MJ, Yoon IJ, Park SH. Effects of virtual reality on upper extremity function and activities of daily living performance in acute stroke: a double-blind randomized clinical trial. Neuro Rehabilitation. 2012;31(4):379–385.
Ma HI, Hwang WJ, Fang JJ, et al. Effects of virtual reality training on functional reaching movements in people with Parkinson’s disease: a randomized controlled pilot trial. Clin Rehabil. 2011;25(10):892–902.
Betker AL, Desai A, Nett C, Kapadia N, Szturm T. Game-based exercises for dynamic short-sitting balance rehabilitation of people with chronic spinal cord and traumatic brain injuries. Phys Ther. 2007;87(10):1389–1398.
Cho KH, Lee KJ, Song CH. Virtual-reality balance training with a video-game system improves dynamic balance in chronic stroke patients. Tohoku J Exp Med. 2012;228(1):69–74.
Heiden E, Lajoie Y. Games-based biofeedback training and the attentional demands of balance in older adults. Aging Clin Exp Res. 2010;22(5–6):367–373.
Kliem A, Wiemeyer J. Comparison of a traditional and a video game based balance training program. Int J Comput Sci Sport. 2010;9(2):80–91.
Shema SR, Brozgol M, Dorfman M, et al. Clinical experience using a 5-week treadmill training program with virtual reality to enhance gait in an ambulatory physical therapy service. Phys Ther. 2014;94(9):1319–1326.
Batson CD, Brady RA, Peters BT, et al. Gait training improves performance in healthy adults exposed to novel sensory discordant conditions. Exp Brain Res. 2011;209(4):515–524.
Brütsch K, Koenig A, Zimmerli L, et al. Virtual reality for enhancement of robot-assisted gait training in children with central gait disorders. J Rehabil Med. 2011;43(6):493–499.
Deutsch JE, Merians AS, Adamovich S, Poizner H, Burdea GC. Development and application of virtual reality technology to improve hand use and gait of individuals post-stroke. Restor Neurol Neurosci. 2004;22(3–5):371–386.
Fung J, Richards CL, Malouin F, Mcfadyen BJ, Lamontagne A. A treadmill and motion coupled virtual reality system for gait training post-stroke. Cyberpsychol Behav. 2006;9(2):157–162.
Mirelman A, Maidan I, Herman T, Deutsch JE, Giladi N, Hausdorff JM. Virtual reality for gait training: can it induce motor learning to enhance complex walking and reduce fall risk in patients with Parkinson’s disease? J Gerontol: Ser A. 2011;66(2):234–240.
Chirico A, Lucidi F, de Laurentiis M, Milanese C, Napoli A, Giordano A. Virtual reality in health system: beyond entertainment. A mini-review on the efficacy of VR during cancer treatment. J Cell Physiol. 2016;231(2):275–287.
Oyama H, Ohsuga M, Tatsuno Y, Katsumata N. Evaluation of the psycho-oncological effectiveness of the bedside wellness system. Cyber Psychology Behav. 1999;2(1):81–84.
Schneider SM, Ellis M, Coombs WT, Shonkwiler EL, Folsom LC. Virtual reality intervention for older women with breast cancer. Cyber Psychology Behav. 2003;6(3):301–307.
Schneider SM, Kisby CK, Flint EP. Effect of virtual reality on time perception in patients receiving chemotherapy. Support Care Cancer. 2011;19(4):555–564.
Baños RM, Espinoza M, García-Palacios A, et al. A positive psychological intervention using virtual reality for patients with advanced cancer in a hospital setting: a pilot study to assess feasibility. Support Care Cancer. 2013;21(1):263–270.
Espinoza M, Baños RM, Garcia-Palacios A, et al. Promotion of emotional wellbeing in oncology inpatients using VR. In: Wiederhold BK, Riva G, editors. Annual Review of Cybertherapy and Telemedicine. Amsterdam: Interactive Media Institute and IOS Press; 2012:53–57.
Valmaggia LR, Latif L, Kempton MJ, Rus-Calafell M. Virtual reality in the psychological treatment for mental health problems: an systematic review of recent evidence. Psychiatry Res. 2016;236:189–195.
Freeman D, Reeve S, Robinson A, et al. Virtual reality in the assessment, understanding, and treatment of mental health disorders. Psychol Med. 2017;47(14):2393–2400.
Riva G. Virtual environment for body image modification: virtual reality system for the treatment of body image disturbances. Comput Human Behav. 1998;14(3):477–490.
Cesa GL, Manzoni GM, Bacchetta M, et al. Virtual reality for enhancing the cognitive behavioral treatment of obesity with binge eating disorder: randomized controlled study with one-year follow-up. J Med Internet Res. 2013;15(6):e113.
Riva G. The key to unlocking the virtual body: virtual reality in the treatment of obesity and eating disorders. J Diabetes Sci Technol. 2011;(2):283–292.
Ferrer-García M, Gutiérrez-Maldonado J. The use of virtual reality in the study, assessment, and treatment of body image in eating disorders and nonclinical samples: a review of the literature. Body Image. 2012;9(1):1–11.
Ferrer-Garcia M, Gutierrez-Maldonado J, Treasure J, Vilalta-Abella F. Craving for food in virtual reality scenarios in non-clinical sample: analysis of its relationship with body mass index and eating disorder symptoms. Eur Eat Disord Rev. 2015;23(5):371–378.
de Carvalho MR, Dias TRS, Duchesne M, Nardi AE, Appolinario JC. Virtual reality as a promising strategy in the assessment and treatment of bulimia nervosa and binge eating disorder: a systematic review. Behav Sci. 2017;7(3):43.
Manzoni GM, Pagnini F, Gorini A, et al. Can relaxation training reduce emotional eating in women with obesity? An exploratory study with 3 months of follow-up. J Am Diet Assoc. 2009;109(8):1427–1432.
Botella C, García-Palacios A, Villa H, et al. Virtual reality exposure in the treatment of panic disorder and agoraphobia: a controlled study. Clin Psychol Psychother. 2007;14(3):164–175.
Malbos E, Rapee RM, Kavakli M. A controlled study of agoraphobia and the independent effect of virtual reality exposure therapy. Austr N Z J Psychiatry. 2013;47(2):160–168.
Castro WP, Roca Sánchez MJ, Pitti González CT, Bethencourt JM, de La Fuente Portero JA, Marco RG. Cognitive-behavioral treatment and antidepressants combined with virtual reality exposure for patients with chronic agoraphobia. Int J Clin Health Psychol. 2014;14(1):9–17.
Shiban Y, Pauli P, Mühlberger A. Effect of multiple context exposure on renewal in spider phobia. Behav Res Ther. 2013;51(2):68–74.
Shiban Y, Schelhorn I, Pauli P, Mühlberger A. Effect of combined multiple contexts and multiple stimuli exposure in spider phobia: a randomized clinical trial in virtual reality. Behav Res Ther. 2015;71:45–53.
Cardo RA, David OA, David DO. Virtual reality exposure therapy in flight anxiety. Comput Human Behav. 2017;72(C):371–380.
Maples-Keller JL, Bunnell BE, Kim SJ, Rothbaum BO. The use of virtual reality technology in the treatment of anxiety and other psychiatric disorders. Harv Rev Psychiatry. 2017;25(3):103–113.
Anderson PL, Edwards SM, Goodnight JR. Virtual reality and exposure group therapy for social anxiety disorder: results from a 4–6 year follow-up. Cognit Ther Res. 2017;41(2):230–236.
Mishkind MC, Norr AM, Katz AC, Reger GM. Review of virtual reality treatment in psychiatry: evidence versus current diffusion and use. Curr Psychiatry Rep. 2017;19(11):80.
Difede J, Hoffman HG. Virtual reality exposure therapy for World Trade Center Post-traumatic Stress Disorder: a case report. Cyberpsychol Behav. 2002;5(6):529–535.
Rothbaum BO, Hodges LF, Ready D, Graap K, Alarcon RD. Virtual reality exposure therapy for Vietnam veterans with posttraumatic stress disorder. J Clin Psychiatry. 2001;62(8):617–622.
Ponsford J, Lee NK, Wong D, et al. Efficacy of motivational interviewing and cognitive behavioral therapy for anxiety and depression symptoms following traumatic brain injury. Psychol Med. 2016;46(5):1079–1090.
American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. 5th ed. Washington, DC: American Psychiatric Association Publishing; 2013.
Shah LB, Torres S, Kannusamy P, Chng CM, He HG, Klainin-Yobas P. Efficacy of the virtual reality-based stress management program on stress-related variables in people with mood disorders: the feasibility study. Arch Psychiatr Nurs. 2015;29(1):6–13.
Falconer CJ, Slater M, Rovira A, et al. Embodying compassion: a virtual reality paradigm for overcoming excessive self-criticism. PloS one. 2014;9(11):e111933.
Falconer CJ, Rovira A, King JA, et al. Embodying self-compassion within virtual reality and its effects on patients with depression. BJPsych Open. 2016;2(1):74–80.
Dehn LB, Kater L, Piefke M, Botsch M, Driessen M, Beblo T. Training in a comprehensive everyday-like virtual reality environment compared to computerized cognitive training for patients with depression. Comput Human Behav. 2018;79:40–52.
Berman MG, Kross E, Krpan KM, et al. Interacting with nature improves cognition and affect for individuals with depression. J Affect Disord. 2012;140(3):300–305.
Coffey MJ, Roy-Byrne P, Marder S, Solomon D. Catatonia: treatment and prognosis. Uptodate. 2016;11:1–11.
De Luca R, Russo M, Naro A, et al. Effects of virtual reality-based training with BTs-Nirvana on functional recovery in stroke patients: preliminary considerations. Int J Neurosci. 2018;128(9):791–796.
De Luca R, Torrisi M, Piccolo A, et al. Improving post-stroke cognitive and behavioral abnormalities by using virtual reality: a case report on a novel use of nirvana. Appl Neuropsychol: Adult. 2018;25(6):581–585.
Larson EB, Ramaiya M, Zollman FS, et al. Tolerance of a virtual reality intervention for attention remediation in persons with severe TBI. Brain Inj. 2011;25(3):274–281.
Faria AL, Andrade A, Soares L, I Badia SB. Benefits of virtual reality based cognitive rehabilitation through simulated activities of daily living: a randomized controlled trial with stroke patients. J Neuroeng Rehabil. 2016;13(1):96.
Shin H, Kim K. Virtual reality for cognitive rehabilitation after brain injury: a systematic review. J Phys Ther Sci. 2015;27(9):2999–3002.
Panetta C. Top Trends in the Gartner Hype Cycle for Emerging Technologies, 2017. Available from: https://www.gartner.com/smarterwithgartner/top-trends-in-the-gartner-hype-cycle-for-emerging-technologies-2017/2017. Accessed October 23, 2018.
Long B, Seah SA, Carter T, Subramanian S. Rendering volumetric haptic shapes in mid-air using ultrasound. ACM Trans Graph. 2014;33(6):181.
Tsigos C, Chrousos GP. Hypothalamic-pituitary-adrenal axis, neuroendocrine factors and stress. J Psychosom Res. 2002;53(4):865–871.
Egorov AI, Griffin SM, Converse RR, et al. Vegetated land cover near residence is associated with reduced allostatic load and improved biomarkers of neuroendocrine, metabolic and immune functions. Environ Res. 2017;158:508–521.
Annerstedt M, Jönsson P, Wallergård M, et al. Inducing physiological stress recovery with sounds of nature in a virtual reality forest – results from a pilot study. Physiol Behav. 2013;118:240–250.
Bratman GN, Hamilton JP, Hahn KS, Daily GC, Gross JJ. Nature experience reduces rumination and subgenual prefrontal cortex activation. Proc Natl Acad Sci U S A. 2015;112(28):8567–8572.
Aspinall P, Mavros P, Coyne R, Roe J. The urban brain: analysing outdoor physical activity with mobile EEG. Br J Sports Med. 2015;49(4):272–276.
Nieminen T, Martelin T, Koskinen S, Aro H, Alanen E, Hyyppä MT. Social capital as a determinant of self-rated health and psychological well-being. Int J Public Health. 2010;55(6):531–542.
Castro SA, Zautra AJ. Humanization of social relations: nourishing health and resilience through greater humanity. J Theor Philos Psychol. 2016;36(2):64–80.
Pantell M, Rehkopf D, Jutte D, Syme SL, Balmes J, Adler N. Social isolation: a predictor of mortality comparable to traditional clinical risk factors. Am J Public Health. 2013;103(11):2056–2062.
Yang YC, Boen C, Gerken K, Li T, Schorpp K, Harris KM. Social relationships and physiological determinants of longevity across the human life span. Proc Nat Acad Sci. 2016;113(3):578–583.
de Vries S, van Dillen SM, Groenewegen PP, Spreeuwenberg P. Streetscape greenery and health: stress, social cohesion and physical activity as mediators. Soc Sci Med. 2013;94:26–33.
Seeland K, Dübendorfer S, Hansmann R. Making friends in Zurich’s urban forests and parks: the role of public green space for social inclusion of youths from different cultures. For Policy Econ. 2009;11(1):10–17.
Orban E, Sutcliffe R, Dragano N, Jöckel KH, Moebus S. Residential surrounding greenness, self-rated health and interrelations with aspects of neighborhood environment and social relations. J Urban Health. 2017;94(2):158–169.
Ruijsbroek A, Mohnen SM, Droomers M, et al. Neighbourhood green space, social environment and mental health: an examination in four European cities. Int J Public Health. 2017;62(6):657–667.
Maas J, van Dillen SME, Verheij RA, Groenewegen PP. Social contacts as a possible mechanism behind the relation between green space and health. Health Place. 2009;15(2):586–595.
Ward Thompson C, Aspinall P, Roe J, Robertson L, Miller D. Mitigating stress and supporting health in deprived urban communities: the importance of green space and the social environment. Int J Environ Res Public Health. 2016;13(4):440.
Ballantyne A, Trenwith L, Zubrinich S, Corlis M. “I feel less lonely”: what older people say about participating in a social networking website. Qual Ageing Older Adults. 2010;11(3):25–35.
Tsai HH, Tsai YF, Wang HH, Chang YC, Chu HH. Videoconference program enhances social support, loneliness, and depressive status of elderly nursing home residents. Aging Ment Health. 2010;14(8):947–954.
Blažun H, Saranto K, Rissanen S. Impact of computer training courses on reduction of loneliness of older people in Finland and Slovenia. Comput Human Behav. 2012;28(4):1202–1212.
Hawkley LC, Kocherginsky M. Transitions in loneliness among older adults: a 5-year follow-up in the National Social Life, Health, and Aging Project. Res Aging. 2018;40(4):365–387.
Shankar A, McMunn A, Demakakos P, Hamer M, Steptoe A. Social isolation and loneliness: prospective associations with functional status in older adults. Health Psychol. 2017;36(2):179–187.
Emerson K, Boggero I, Ostir G, Jayawardhana J. Pain as a risk factor for loneliness among older adults. J Aging Health. 2018;30(9):1450–1461.
Barlow MA, Liu SY, Wrosch C. Chronic illness and loneliness in older adulthood: The role of self-protective control strategies. Health Psychol. 2015;34(8):870–879.
Kuo M. How might contact with nature promote human health? Promising mechanisms and a possible central pathway. Front Psychol. 2015;6:1093.
Li Q. Effect of forest bathing trips on human immune function. Environ Health Prev Med. 2010;15(1):9–17.
Rook GA. Regulation of the immune system by biodiversity from the natural environment: an ecosystem service essential to health. Proc Nat Acad Sci. 2013;110(46):18360–18367.
Lynch SV, Wood RA, Boushey H, et al. Effects of early-life exposure to allergens and bacteria on recurrent wheeze and atopy in urban children. J Allergy Clin Immunol. 2014;134(3):593–601.
Dhabhar FS. Effects of stress on immune function: the good, the bad, and the beautiful. Immunol Res. 2014;58(2–3):193–210.
Mcgregor BA, Murphy KM, Albano DL, Ceballos RM. Stress, cortisol, and B lymphocytes: a novel approach to understanding academic stress and immune function. Stress. 2016;19(2):185–191.
Veitch J, Abbott G, Kaczynski AT, Wilhelm Stanis SA, Besenyi GM, Lamb KE. Park availability and physical activity, TV time, and overweight and obesity among women: findings from Australia and the United States. Health Place. 2016;38:96–102.
Christian H, Knuiman M, Divitini M, et al. A longitudinal analysis of the influence of the neighborhood environment on recreational walking within the neighborhood: results from RESIDE. Environ Health Perspect. 2017;125(7):077009.
Dadvand P, Villanueva CM, Font-Ribera L, et al. Risks and benefits of green spaces for children: a cross-sectional study of associations with sedentary behavior, obesity, asthma, and allergy. Environ Health Perspect. 2014;122(12):1329–1335.
Wendel-Vos GC, Schuit AJ, de Niet R, Boshuizen HC, Saris WH, Kromhout D. Factors of the physical environment associated with walking and bicycling. Med Sci Sports Exerc. 2004;36(4):725–730.
Kaczynski AT, Henderson KA. Environmental correlates of physical activity: a review of evidence about parks and recreation. Leis Sci. 2007;29(4):315–354.
Astell-Burt T, Feng X, Kolt GS. Mental health benefits of neighbourhood green space are stronger among physically active adults in middle-to-older age: evidence from 260,061 Australians. Prev Med. 2013;57(5):601–606.
Sugiyama T, Gunn LD, Christian H, et al. Quality of public open spaces and recreational walking. Am J Public Health. 2015;105(12):2490–2495.
Akpinar A. How is quality of urban green spaces associated with physical activity and health? Urban For Urban Green. 2016;16:76–83.
Pietilä M, Neuvonen M, Borodulin K, Korpela K, Sievänen T, Tyrväinen L. Relationships between exposure to urban green spaces, physical activity and self-rated health. J Outdoor Recreat Tourism. 2015;10:44–54.
White MP, Elliott LR, Wheeler BW, Fleming LE. Neighbourhood greenspace is related to physical activity in England, but only for dog owners. Landsc Urban Plan. 2018;174:18–23.
Markevych I, Schoierer J, Hartig T, et al. Exploring pathways linking greenspace to health: theoretical and methodological guidance. Environ Res. 2017;158:301–317.
Kollmuss A, Agyeman J. Mind the gap: why do people act environmentally and what are the barriers to pro-environmental behavior? Environ Educ Res. 2002;8(3):239–260.
Annerstedt van den Bosch M, Depledge MH. Healthy people with nature in mind. BMC Public Health. 2015;15:1232.
Thompson CW, Aspinall P, Montarzino A. The childhood factor: Adult visits to green places and the significance of childhood experience. Environ Behav. 2008;40(1):111–143.
Zelenski JM, Dopko RL, Capaldi CA. Cooperation is in our nature: nature exposure may promote cooperative and environmentally sustainable behavior. J Environ Psychol. 2015;42:24–31.
Yuen GS, Bhutani S, Lucas BJ, et al. Apathy in late-life depression: common, persistent, and disabling. Am J Geriatr Psychiatry. 2015;23(5):488–494.
Cherrie MP, Wheeler BW, White MP, Sarran CE, Osborne NJ. Coastal climate is associated with elevated solar irradiance and higher 25(OH)D level. Environ Int. 2015;77:76–84.
De Rui M, Toffanello ED, Veronese N, et al. Vitamin D deficiency and leisure time activities in the elderly: are all pastimes the same? PLoS One. 2014;9(4):e94805.
Liu D, Fernandez BO, Hamilton A, et al. UVA irradiation of human skin vasodilates arterial vasculature and lowers blood pressure independently of nitric oxide synthase. J Invest Dermatol. 2014;134(7):1839–1846.
Leproult R, Copinschi G, Buxton O, van Cauter E. Sleep loss results in an elevation of cortisol levels the next evening. Sleep. 1997;20(10):865–870.
Frey DJ, Fleshner M, Wright KP. The effects of 40 hours of total sleep deprivation on inflammatory markers in healthy young adults. Brain Behav Immun. 2007;21(8):1050–1057.
Mullington JM, Haack M, Toth M, Serrador JM, Meier-Ewert HK. Cardiovascular, inflammatory, and metabolic consequences of sleep deprivation. Prog Cardiovasc Dis. 2009;51(4):294–302.
Astell-Burt T, Feng X, Kolt GS. Does access to neighbourhood green space promote a healthy duration of sleep? Novel findings from a cross-sectional study of 259 319 Australians. BMJ Open. 2013;3(8):e003094.
Grigsby-Toussaint DS, Turi KN, Krupa M, Williams NJ, Pandi-Perumal SR, Jean-Louis G. Sleep insufficiency and the natural environment: results from the US Behavioral Risk Factor Surveillance System survey. Prev Med. 2015;78:78–84.
Golden RN, Gaynes BN, Ekstrom RD, et al. The efficacy of light therapy in the treatment of mood disorders: a review and meta-analysis of the evidence. Am J Psychiatry. 2005;162(4):656–662.
Gujjar KR, van Wijk A, Sharma R, de Jongh A. Virtual reality exposure therapy for the treatment of dental phobia: A controlled feasibility study. Behav Cogn Psychother. 2018;46(3):367–373.
Rus-Calafell M, Garety P, Sason E, Craig TJK, Valmaggia LR. Virtual reality in the assessment and treatment of psychosis: a systematic review of its utility, acceptability and effectiveness. Psychol Med. 2018;48(3):362–391.
Palmisano S, Mursic R, Kim J. Vection and cybersickness generated by head-and-display motion in the Oculus Rift. Displays. 2017;46:1–8.
Kim A, Darakjian N, Finley JM. Walking in fully immersive virtual environments: an evaluation of potential adverse effects in older adults and individuals with Parkinson’s disease. J Neuroeng Rehabil. 2017;14(1):16.
Berard J, Fung J, Lamontagne A. Impact of aging on visual reweighting during locomotion. Clin Neurophysiol. 2012;123(7):1422–1428.
Berard JR, Fung J, Lamontagne A. Evidence for the use of rotational optic flow cues for locomotor steering in healthy older adults. J Neurophysiol. 2011;106(3):1089–1096.
de Dieuleveult AL, Siemonsma PC, van Erp JB, Brouwer AM. Effects of aging in multisensory integration: a systematic review. Front Aging Neurosci. 2017;9:80.
Ramkhalawansingh R, Keshavarz B, Haycock B, Shahab S, Campos JL. Examining the effect of age on visual-vestibular self-motion perception using a driving paradigm. Perception. 2017;46(5):566–585.
Niehorster DC, Li L, Lappe M. The accuracy and precision of position and orientation tracking in the HTC VIVE virtual reality system for scientific research. Iperception. 2017;8(3):2041669517708205.
Keshavarz B, Speck M, Haycock B, Berti S. Effect of different display types on vection and its interaction with motion direction and field dependence. Iperception. 2017;8(3):2041669517707768.
Matas NA, Nettelbeck T, Burns NR. Dropout during a driving simulator study: a survival analysis. J Safety Res. 2015;55:159–169.
Mosadeghi S, Reid MW, Martinez B, Rosen BT, Spiegel BM. Feasibility of an immersive virtual reality intervention for hospitalized patients: an observational cohort study. JMIR Ment Health. 2016;3(2):e28.
Ford CG, Manegold EM, Randall CL, Aballay AM, Duncan CL. Assessing the feasibility of implementing low-cost virtual reality therapy during routine burn care. Burns. 2018;44(4):886–895.
Dockx K, Alcock L, Bekkers E, et al. Fall-prone older people’s attitudes towards the use of virtual reality technology for fall prevention. Gerontology. 2017;63(6):590–598.
Zhang MW, Ho RC. Smartphone applications for immersive virtual reality therapy for internet addiction and internet gaming disorder. Technol Health Care. 2017;25(2):367–372.
Park SY, Kim SM, Roh S, et al. The effects of a virtual reality treatment program for online gaming addiction. Comput Methods Programs Biomed. 2016;129:99–108.
Davis N. Long-term effects of virtual reality use need more research, say scientists. The Guardian, International edition. 2016. Available from: https://www.theguardian.com/technology/2016/mar/19/long-term-effects-of-virtual-reality-use-need-more-research-say-scientists. Accessed October 23, 2018.
Langley H. We need to look more carefully into the long-term effects of VR . 2017. Available from: https://www.wareable.com/vr/vr-long-term-brain-eyes-effects-6674. Accessed October 23, 2018.
Yu CP, Lee HY, Luo XY. The effect of virtual reality forest and urban environments on physiological and psychological responses. Urban Forestry & Urban Greening. 2018;35:106–114.
Valtchanov D, Barton KR, Ellard C. Restorative effects of virtual nature settings. Cyberpsychol Behav Soc Netw. 2010;13(5):503–512.
Barton J, Pretty J. What is the best dose of nature and green exercise for improving mental health? A multi-study analysis. Environ Sci Technol. 2010;44(10):3947–3955.
Ulrich RS, Simons RF, Losito BD, Fiorito E, Miles MA, Zelson M. Stress recovery during exposure to natural and urban environments. J Environ Psychol. 1991;11(3):201–230.
Song C, Ikei H, Miyazaki Y. Physiological effects of visual stimulation with forest imagery. Int J Environ Res Public Health. 2018;15(2):213.
This work is published and licensed by Dove Medical Press Limited. The full terms of this license are available at https://www.dovepress.com/terms.php and incorporate the Creative Commons Attribution - Non Commercial (unported, v3.0) License. By accessing the work you hereby accept the Terms. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed. For permission for commercial use of this work, please see paragraphs 4.2 and 5 of our Terms.Download Article [PDF]