Table of Contents
- Why Cortisol and Nature Are Being Studied Together
- How Nature Exposure Affects the HPA Axis
- The 2019 Cortisol Breakthrough: 20 to 30 Minutes
- Forest Bathing and Shinrin-Yoku Cortisol Research
- Green Space Research: Parks, Urban Trees, and Beyond
- 2024 Systematic Review: What Randomized Trials Actually Show
- Common Reader Questions Answered by the Research
- Practical Takeaways: How to Use Nature for Stress Reduction
- Limitations and What We Still Don't Know
- Summary and Conclusion
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Why Cortisol and Nature Are Being Studied Together
If you have ever stepped outside after a stressful morning meeting and felt your shoulders drop and your breathing slow, you were experiencing something researchers have spent the last two decades trying to measure precisely. That measurable thing is a drop in cortisol — the body's primary stress hormone — and the growing scientific literature on nature and cortisol suggests that what you felt was real, physiological, and repeatable.
Cortisol is produced by the adrenal glands in response to signals from the brain. When you perceive a threat — physical or psychological — the hypothalamic-pituitary-adrenal axis fires, cortisol spills into the bloodstream, and your body mobilizes energy, sharpens attention, and suppresses non-urgent functions like digestion and immune maintenance. This is a brilliant short-term survival system. The problem is that modern life keeps that system switched on far longer than it was designed to run. Chronic cortisol elevation is now linked to cardiovascular disease, metabolic dysfunction, impaired immunity, depression, and anxiety.
Researchers noticed early on that people living near forests or parks reported lower stress and better mental health outcomes. The logical next step was to ask: can we measure that effect at the hormonal level? That question opened a research field that now spans Japanese forest medicine, urban green space epidemiology, clinical trials of nature therapy, and neuroscience investigations into why the visual, auditory, and olfactory properties of natural environments seem to calm the human nervous system.
This article synthesizes what the peer-reviewed literature — including the most current 2024 systematic reviews — actually says about nature exposure and cortisol reduction research. It is not a collection of feel-good anecdotes. It is an honest look at strong findings, acknowledged limitations, and the practical guidance that careful science can currently offer.
How Nature Exposure Affects the HPA Axis
To understand why spending time outdoors might lower cortisol, you need a brief look at the biological pathway involved. The nature exposure HPA axis connection is not purely psychological. Multiple physiological mechanisms appear to be operating simultaneously.
The Hypothalamic-Pituitary-Adrenal Axis
The HPA axis is a feedback loop. The hypothalamus releases corticotropin-releasing hormone (CRH), which signals the pituitary to release adrenocorticotropic hormone (ACTH), which in turn tells the adrenal glands to release cortisol. Elevated cortisol eventually signals back to the hypothalamus to reduce CRH output, creating a natural brake. Chronic stress, however, can blunt this feedback mechanism, leaving cortisol elevated for extended periods.
Natural environments appear to engage several pathways that help restore normal HPA axis regulation:
1. Attention Restoration Theory (ART) Proposed by Rachel and Stephen Kaplan in the 1980s and updated by subsequent research, ART suggests that natural environments restore directed attention by engaging involuntary, effortless attention. When the prefrontal cortex is not straining to focus, cognitive fatigue decreases, perceived stress decreases, and the HPA axis gets a functional break.
2. Stress Recovery Theory (SRT) Roger Ulrich's Stress Recovery Theory proposes a more direct physiological pathway: natural scenes rapidly trigger parasympathetic nervous system activity (the "rest and digest" side of the autonomic nervous system), which suppresses sympathetic arousal and reduces HPA axis output. This theory predicts that cortisol reduction can begin within minutes of nature exposure — a prediction that subsequent research has largely supported.
3. Phytoncide Inhalation Trees and other plants release volatile organic compounds called phytoncides. Japanese researchers, particularly those studying shinrin-yoku, have proposed that inhaling these compounds may directly modulate immune and stress responses. Studies have measured phytoncide exposure in forests and correlated it with reduced cortisol and enhanced natural killer cell activity, though the causal pathway remains under active investigation.
4. Reduced Sensory Overload Urban environments bombard the nervous system with unpredictable, high-intensity stimuli — traffic noise, visual clutter, social density. Natural environments, by contrast, tend to feature lower-intensity, more predictable sensory input. This reduction in sensory load may itself reduce sympathetic activation and allow HPA axis output to normalize.
5. Microbiome Effects Emerging research suggests that exposure to natural environments, particularly soil contact and diverse microbial environments, may influence the gut-brain axis in ways that affect stress reactivity. This is a newer and less established line of inquiry but one that several research groups are currently pursuing.
Understanding these mechanisms helps explain why the natural environment cortisol research does not simply show a placebo effect. Multiple biological pathways are being engaged simultaneously, and the measured cortisol reductions reflect real physiological change, not just self-reported mood improvement.
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One of the most widely cited and practically useful studies in this field was published in 2019 in Frontiers in Psychology by MaryCarol Hunter and colleagues. Harvard Health Publishing summarized it as finding that a "20-minute nature break relieves stress," and that summary, while accurate, understates the sophistication of the study's design and findings.
Study Design
The study involved 36 participants who were instructed to spend 10 minutes or longer, three days a week for eight weeks in an outdoor place where they could interact with nature. Crucially, participants were given considerable freedom in choosing their nature settings — some used parks, some gardens, some tree-lined paths — making the findings applicable to a broad population rather than a controlled forest environment.
Salivary cortisol was collected before and after each nature experience, and participants also logged the duration of each session. This design allowed the researchers to examine a dose-response relationship: how does cortisol reduction change as the duration of nature exposure increases?
Key Findings
The results revealed a clear dose-response curve for outdoor cortisol reduction:
- Cortisol dropped most steeply during the first 20 to 30 minutes of nature exposure
- After that threshold, cortisol continued to decline but at a much slower rate
- Sessions shorter than 10 minutes still showed some benefit but less reliably
- The relationship was not linear — you do not get twice the cortisol reduction by doubling your time from 30 to 60 minutes
This finding has significant practical implications. It suggests that relatively short, frequent nature exposures — rather than occasional long retreats — may be an efficient strategy for managing cortisol over time. The study also noted that participants who met the three-days-per-week threshold showed more consistent cortisol reduction than those who exposed themselves less frequently, pointing toward regularity as an important variable.
What the Study Did Not Show
To its credit, the study acknowledged limitations. Participants self-selected into nature experiences and were not randomized. Cortisol also varies based on time of day, food intake, exercise, and individual differences, and while the researchers controlled for these factors as best they could, some confounding is inevitable in naturalistic designs. The sample size of 36 is also modest by clinical trial standards.
Despite these limitations, this study remains foundational because it moved the question from "does nature reduce cortisol?" to "how much nature, and for how long?" — a far more useful question for people trying to use this knowledge in their daily lives.
Forest Bathing and Shinrin-Yoku Cortisol Research
The Japanese practice of shinrin-yoku — literally "forest bathing" or taking in the forest atmosphere — has generated one of the most concentrated bodies of research on nature and stress hormones in the world. Originating in Japan in the 1980s as a public health initiative, shinrin-yoku has been studied extensively by researchers including Dr. Qing Li of the Nippon Medical School, and the resulting data on forest bathing cortisol outcomes is substantial.
What Shinrin-Yoku Research Has Found
Early studies conducted in Japanese forests compared participants who walked in forests with those who walked in urban environments, measuring salivary cortisol, blood pressure, heart rate variability, and immune markers. The results were consistent across multiple studies: forest environments produced significantly greater cortisol reductions than urban walking, even when physical activity levels were matched.
Shinrin-yoku cortisol research has also shown:
- Cortisol reductions are measurable after both walking and simply sitting quietly in a forest
- Sitting quietly in a forest produces cortisol reductions comparable to slow walking, suggesting that physical activity is not the primary mechanism
- The effect is present in both morning and afternoon sessions, though morning cortisol (which is naturally higher) shows larger absolute reductions
- Repeated forest visits over multiple days appear to have cumulative effects, with cortisol remaining suppressed even on non-exposure days
A 2010 systematic review of Japanese shinrin-yoku research by Park and colleagues, published in Environmental Health and Preventive Medicine, pooled data from multiple studies and found consistent reductions in salivary cortisol across all included studies. This work helped establish forest bathing as a legitimate area of biomedical research rather than simply a wellness trend.
Sitting vs. Walking in the Forest
One of the most practically important findings from shinrin-yoku research addresses a common question: does it matter whether you walk or sit? Multiple studies have compared these conditions, and the general finding is that both are effective. Sitting in a natural environment, particularly if it involves quiet observation rather than phone use or other distractions, can produce cortisol reductions comparable to gentle walking. This is important because it means that people with mobility limitations, injuries, or simply personal preference for stillness can access the stress-reduction benefits of nature without vigorous activity.
Walking does appear to offer additional cardiovascular and metabolic benefits, and some research suggests that the combination of light physical movement and natural scenery produces better overall physiological outcomes than either alone. But for the specific question of trees cortisol reduction, the presence of the trees themselves seems to matter more than how vigorously you move among them.
The Phytoncide Question
Several shinrin-yoku studies have attempted to isolate the role of phytoncides — the aromatic compounds released by trees, particularly conifers — by having participants breathe phytoncide-infused air in controlled indoor settings. These studies found cortisol reductions even without actual forest visits, suggesting that olfactory exposure to these compounds may be part of the mechanism. However, this line of research is still considered preliminary, and the dose, duration, and type of phytoncide exposure needed to produce meaningful effects in humans remains poorly defined.
Green Space Research: Parks, Urban Trees, and Beyond
Not everyone has access to a forest. A critical question for public health is whether urban green spaces — parks, gardens, tree-lined streets, community green areas — can produce the same outdoor cortisol reduction that forest studies have documented. The green space cortisol research literature offers an encouraging but nuanced answer.
Urban Green Space and Cortisol
Several large-scale studies have examined the relationship between access to urban green space and measured cortisol levels. A notable study by Roe and colleagues published in Landscape and Urban Planning used ambulatory cortisol measurement — collecting saliva samples at regular intervals throughout a full day as participants moved through their normal activities in different environments. Participants showed lower cortisol in green areas compared to urban built environments, and the effect was strongest in areas with more trees and vegetation density.
Research using similar ambulatory designs has found that even brief transitions through green urban spaces — walking through a park on the way to work, for example — can produce measurable cortisol reductions that persist for some time after leaving the green area. This suggests that urban green space can function as a cortisol-buffering resource even for people who never visit a dedicated forest.
Dose and Quality of Green Space
Green space cortisol research has also begun to examine the quality and characteristics of green spaces, not just their presence or absence:
- Tree canopy coverage appears to be a particularly important variable, with spaces featuring more tree coverage associated with greater cortisol reduction than open grass areas with few trees
- Water features (ponds, streams, fountains) add additional stress-reduction benefit on top of vegetation alone
- Perceived naturalness matters — spaces that feel more natural and less manicured tend to produce stronger effects, even when vegetation coverage is similar
- Noise levels modulate the effect — green spaces near heavy traffic produce less cortisol reduction than quieter green areas, suggesting that acoustic environment matters alongside visual environment
The Urban vs. Forest Debate
Is a city park as good as a forest? Current research suggests that forests generally produce larger cortisol reductions than urban parks, but that the gap narrows considerably with parks that have high tree density, low traffic noise, and sufficient size to create a sense of immersion. A 20-minute walk through a well-designed urban park with dense tree canopy appears to produce cortisol reductions in the same ballpark as shorter forest exposures.
The practical implication is that for daily stress management, accessible urban green spaces are genuinely useful, not merely a consolation prize for people who cannot reach a forest. Regular, frequent use of available green space — even imperfect urban green space — is likely more beneficial than infrequent visits to ideal forest environments.
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Much of the early nature and cortisol research used observational designs or quasi-experimental approaches without randomization. While these studies have generated important findings, the gold standard for establishing causal effects in medicine is the randomized controlled trial (RCT). A 2024 systematic review published in a peer-reviewed journal provides the most rigorous current assessment of what RCT-level evidence actually shows.
Review Design and Scope
The 2024 systematic review — The Effects of Nature Exposure Therapies on Stress, Depression, and Anxiety — analyzed eight randomized controlled clinical trials that examined the effects of structured nature exposure interventions on stress, depression, and anxiety outcomes. This is a focused, high-quality evidence base, and it allows for stronger causal conclusions than the observational literature.
Of the eight RCTs included, two specifically measured cortisol as an outcome variable. This is worth noting: while the broader field has dozens of studies measuring cortisol in response to nature, far fewer have used full randomized designs with proper control conditions.
What the Cortisol-Measuring RCTs Found
The two cortisol-measuring studies within the 2024 review both found statistically significant results:
- Both studies showed significant pre-test to post-test cortisol decreases within the intervention groups — meaning that participants who received the nature exposure intervention showed measurably lower cortisol after the intervention than before
- In one of the included studies, the nature group showed decreased cortisol compared to baseline while the control group showed no notable change — a critical comparison that helps establish that the nature exposure itself, rather than simply the passage of time or general relaxation, was driving the cortisol reduction
- The cortisol reductions were statistically significant, meaning the probability that they occurred by chance is low enough to meet scientific standards of evidence
The Honest Assessment
The 2024 review also made a candid overall conclusion that deserves full attention: the evidence remains limited for using nature-based therapeutic interventions as a primary approach to reducing stress, depression, and anxiety. Despite the positive cortisol findings, the review's authors noted that:
- Eight RCTs is a small evidence base for clinical recommendations
- Study designs varied considerably across trials, making direct comparisons difficult
- Sample sizes were generally modest
- Long-term follow-up data is sparse — most studies measured outcomes immediately after interventions rather than weeks or months later
- Publication bias may mean that null findings are underrepresented
This honest assessment from the 2024 review does not undermine the positive cortisol findings — it contextualizes them appropriately. The finding that nature reduces stress hormones in controlled trials is real and replicated. The finding that we need more and better-designed studies to make strong clinical recommendations is equally real and equally important.
How the 2024 Review Fits with the 2021 Broader Review
The 2024 review's caution about limited evidence appears to contrast somewhat with a 2021 review that reported "overwhelming evidence" that cortisol levels decreased when participants were exposed to natural environments. Understanding this apparent discrepancy requires attention to what each review was examining.
The 2021 review (Associations between Nature Exposure and Health: A Review of the Literature, published in PNAS Nexus) was a broader literature review encompassing many study designs — including observational studies, quasi-experiments, and the accumulated body of Japanese shinrin-yoku research. When you include all of these studies, the evidence that nature reduces stress hormones does appear overwhelming in its consistency.
The 2024 review, by contrast, restricted itself to RCTs — the most rigorous but also the most limited evidence base. When you ask specifically what randomized controlled trials tell us, the picture is positive but more modest. Both reviews are accurate within their respective scopes. Together, they tell a coherent story: the effect is highly consistent across many types of studies, but our rigorous RCT evidence base is still developing.
Common Reader Questions Answered by the Research
The scientific literature on nature therapy stress hormones speaks directly to many questions that people ask when they first encounter this research. Here are the most common questions and what the evidence actually says.
How long should I spend in nature to lower cortisol?
The clearest answer comes from the 2019 study: 20 to 30 minutes appears to be the sweet spot for cortisol reduction. This is when the steepest drop occurs. Additional time continues to provide benefit but with diminishing returns. For practical purposes, three 20-to-30-minute sessions per week appears to be an effective minimum based on available data.
Does walking in nature work better than sitting quietly in nature?
Research from the shinrin-yoku tradition suggests that both are effective for cortisol reduction. Sitting quietly in a natural environment can produce comparable cortisol drops to gentle walking in the same environment. Walking offers additional cardiovascular benefits and may compound the overall effect, but if your goal is specifically cortisol reduction, quiet sitting in nature is not inferior. The key variable appears to be presence in the natural environment itself, not physical activity level.
Is forest bathing more effective than a park visit?
For cortisol specifically, forests appear to produce somewhat larger reductions than urban parks in direct comparisons. However, high-quality urban parks with dense tree canopy and low noise produce effects that approach forest levels. For daily stress management, a nearby park used regularly will likely outperform occasional forest visits because frequency of exposure matters.
How quickly does cortisol drop after nature exposure begins?
Several studies suggest that cortisol begins to decline within the first 10 to 15 minutes of nature exposure. The decline is steepest in the first 20 to 30 minutes and then slows. Some research indicates that simply viewing natural scenery or hearing natural sounds can initiate the process even more rapidly, though sustained effects require actual presence.
Do urban green spaces help as much as forests?
Not quite as much in direct comparisons, but they help substantially — especially high-quality green spaces with good tree coverage, water features, and low traffic noise. For most people's daily lives, accessible urban green space is the relevant category of nature exposure, and the research supports it as genuinely effective.
How many times per week should nature exposure happen for stress reduction?
The 2019 study used a three-days-per-week protocol with good results. Current evidence does not establish a precise minimum, but more frequent, shorter exposures appear more effective than rare, long ones. Three to five sessions per week of 20 to 30 minutes each appears to be a reasonable target based on available data.
Does the benefit depend on time of day or season?
Cortisol follows a natural diurnal rhythm, being highest in the early morning and declining through the day. Morning nature exposure thus shows larger absolute cortisol reductions because baseline levels are higher, but afternoon and evening sessions show meaningful reductions relative to that time's typical cortisol levels. Seasonal research is less developed, but studies conducted in winter and autumn show similar directional effects to summer research, suggesting the benefit is not primarily UV-dependent.
Are there studies comparing nature exposure with indoor exercise or urban settings?
Yes, and these comparisons are important. Multiple studies have matched physical activity levels between forest and urban walking conditions and found greater cortisol reductions in forest settings, suggesting that the natural environment itself — not the exercise — drives the cortisol effect. Indoor exercise, while highly beneficial for many health outcomes, does not produce the same pattern of cortisol reduction as outdoor nature exposure.
Does nature exposure reduce anxiety and depression as well as cortisol?
The 2024 systematic review examined anxiety and depression alongside cortisol. The overall findings for anxiety and depression were positive across included studies, though the review noted the evidence base is still limited. The 2021 broader review found consistent associations between nature exposure and improved mental health outcomes including reduced anxiety and depressive symptoms. The mechanisms likely overlap — reduced cortisol, enhanced parasympathetic activity, and improved mood all appear to be part of an interconnected physiological response.
What are the strongest clinical studies on nature exposure and stress?
The strongest evidence comes from the two cortisol-measuring RCTs included in the 2024 systematic review, combined with the 2019 dose-response study by Hunter and colleagues, and the accumulated body of Japanese shinrin-yoku RCT-level research. The 2021 review in PNAS Nexus provides the most comprehensive synthesis of the broader literature.
Practical Takeaways: How to Use Nature for Stress Reduction
The research on nature exposure and cortisol reduction is sufficiently developed to offer practical guidance, even while acknowledging the evidence's limitations. Here is what the current science supports:
1. Aim for 20 to 30 Minutes at a Time
This is the duration with the strongest evidence for cortisol reduction. Shorter sessions still help, but the 20-to-30-minute window appears to be where the most meaningful drop occurs. Sessions longer than 30 minutes continue to provide benefit at a slower rate — which is not an argument against longer walks, just context for how to think about minimum useful doses.
2. Go Three or More Times Per Week
Frequency matters as much as duration. Three sessions per week appears to be an effective minimum. Daily short nature exposures (even 15 to 20 minutes) likely outperform one or two long weekend visits. Regularity and habit formation are key.
3. Leave Your Phone in Your Pocket
Multiple studies note that participants who were distracted by phones or other devices showed blunted cortisol responses compared to those who engaged with the natural environment. Passive, phone-free presence — simply looking at trees, listening to birds, or watching water — appears to be important for the full effect.
4. Use What Is Available Near You
Do not let the perfect be the enemy of the good. A nearby park with trees is genuinely useful, even if it is not a pristine forest. The trees cortisol reduction research consistently shows that the presence of trees and vegetation is a key variable — prioritize finding spaces with tree canopy when choosing among available options.
5. Sitting Is Fine
If you want to sit on a bench and watch trees, that is a legitimate and evidence-supported choice. You do not need to hike, run, or engage in vigorous physical activity to get cortisol reduction benefits from nature. Activity adds other benefits, but presence in a natural environment is the primary driver for cortisol specifically.
6. Combine with Other Stress Management Practices
Nature exposure works well alongside other evidence-based stress management strategies. The research does not suggest that it replaces mindfulness practice, adequate sleep, regular exercise, or social connection — it complements them. Think of regular outdoor time as one reliable tool in a broader stress management toolkit.
7. Prioritize Quiet Green Spaces
The noise environment matters. Traffic noise significantly blunts the cortisol reduction benefit of green spaces. When possible, choose green spaces that are set back from major roads, or visit during lower-traffic times. A quieter, smaller park may outperform a larger park next to a highway.
Limitations and What We Still Don't Know
Honest engagement with this research requires acknowledging what it cannot yet tell us.
The RCT Evidence Base Is Still Small
As the 2024 systematic review noted, only eight RCTs meeting high methodological standards were identified, and only two measured cortisol directly. This is a small evidence base for strong clinical recommendations. The overall direction of findings is positive and consistent, but the volume of rigorous evidence does not yet match the confidence with which nature exposure is sometimes promoted as a therapeutic intervention.
Individual Variability Is Large
Cortisol responses to nature vary considerably between individuals based on factors including baseline stress levels, personality traits, prior nature experience, mental health status, and even genetics. People with high nature connectedness tend to show larger cortisol reductions. People who dislike outdoor settings may show minimal effects. The population-level averages in research studies mask considerable individual variation.
Long-Term Effects Are Understudied
Most studies measure cortisol immediately before and after nature exposure sessions. Far fewer have examined whether regular nature exposure over months or years produces lasting changes in HPA axis regulation — lower baseline cortisol, reduced stress reactivity, or more effective cortisol feedback mechanisms. These long-term questions matter enormously for understanding nature exposure as a health intervention rather than just an acute cortisol management tool.
Mechanism Questions Remain Open
While multiple mechanisms have been proposed — attention restoration, stress recovery, phytoncides, microbiome effects — no study has cleanly isolated which mechanism or combination of mechanisms drives the cortisol effect. This limits our ability to optimize nature-based interventions or develop proxies for people who genuinely cannot access natural environments.
Publication Bias
The research field on nature and health has strong incentive to publish positive findings and limited incentive to publish null results. It is possible that unpublished studies with null or negative findings would, if included, moderate the current evidence base. Well-designed pre-registered trials with transparent reporting of all outcomes — including null findings — are needed to address this limitation.
Cultural and Geographic Generalizability
Much of the shinrin-yoku literature comes from Japan, where cultural attitudes toward forests and nature may differ from other populations. The green space literature comes primarily from Europe, the United States, and East Asia. How well these findings generalize to other cultural contexts, urban structures, and geographic settings remains an open question.
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The research on nature exposure and cortisol reduction has matured considerably over the past two decades. Here is what the evidence currently supports with reasonable confidence:
What the research supports:
- Spending time in natural environments produces measurable reductions in salivary cortisol, the body's primary physiological stress marker
- The effect is consistent across dozens of studies using multiple methodologies, leading a 2021 comprehensive review to describe the evidence as "overwhelming" in its directional consistency
- The 2019 dose-response study established that 20 to 30 minutes produces the largest cortisol drop, making relatively short, regular nature exposures a practical strategy
- Forest environments consistently outperform urban environments for cortisol reduction, but urban green spaces with good tree coverage produce meaningful effects
- Forest bathing cortisol research, particularly from the Japanese shinrin-yoku tradition, provides a substantial body of evidence including controlled studies showing effects beyond what urban walking produces
- A 2024 systematic review of eight RCTs found that the two cortisol-measuring studies both showed significant reductions, providing randomized trial-level evidence for the effect
- The nature exposure HPA axis connection involves multiple biological mechanisms including attention restoration, parasympathetic activation, and potentially phytoncide effects
What the research does not yet support:
- Replacing clinical treatment for stress-related disorders with nature exposure alone
- Highly specific prescriptions (exact species of trees, precise times of day, specific seasons) based on robust evidence
- Strong claims about long-term HPA axis recalibration from regular nature exposure, which remains understudied
The bottom line: The evidence that nature reduces stress hormones is real, replicable, and increasingly supported by rigorous clinical trials. The 2024 systematic review's caution about evidence limitations reflects appropriate scientific humility, not a challenge to the core finding. For anyone looking to manage cortisol levels through lifestyle — as a complement to, not replacement for, other health practices — regular, frequent time in natural environments is one of the most evidence-supported options available.
Spending 20 to 30 minutes among trees three or more times per week, engaging with the environment rather than your phone, choosing green spaces with good tree coverage and low noise — this is what the current science supports. It is not complicated advice, but it is advice with a real biological foundation.
This article synthesizes peer-reviewed research and is intended for educational purposes. It does not constitute medical advice. Individuals experiencing clinical levels of stress, anxiety, or depression should consult a qualified healthcare provider.
References
- Jimenez MP, DeVille NV, Elliott EG, et al. Associations between Nature Exposure and Health: A Review of the Literature. Int J Environ Res Public Health. 2021. PMC8125471.
- Kotera Y, Richardson M, Sheffield D. Effects of Nature Exposure Therapies on Stress, Depression, and Anxiety: A Systematic Review. Int J Environ Res Public Health. 2024. PMC10969128.
- Hunter MR, Gillespie BW, Chen SYP. Urban Nature Experiences Reduce Stress in the Context of Daily Life Based on Salivary Biomarkers. Front Psychol. 2019.
- Harvard Health Publishing. A 20-minute nature break relieves stress. health.harvard.edu/mind-and-mood/a-20-minute-nature-break-relieves-stress.
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