A growing body of cognitive neuroscience and psychology research suggests that human cognitive performance and neural efficiency are highly sensitive to environmental context. In modern settings characterized by constant stimulation, multitasking, and directed attention demands, cognitive fatigue can accumulate and impair executive function, creativity, and emotional regulation.

Research examining sustained exposure to natural environments suggests that cognition is not only environmentally sensitive, but environmentally recoverable. Time spent in nature appears to support cognitive restoration and adaptive neuroplasticity by reducing cognitive load, restoring attentional capacity, and supporting neural systems involved in executive function. These effects can emerge rapidly and deepen with immersion, highlighting the potential role of thoughtfully designed outdoor environments in supporting long-term cognitive resilience and learning capacity.

1. Extended Nature Immersion and Creative Problem-Solving

Atchley, R. A., Strayer, D. L., & Atchley, P. (2012). Creativity in the wild: Improving creative reasoning through immersion in natural settings. PLOS ONE, 7(12), e51474.

• Experimental study demonstrating that individuals immersed in natural environments for four days showed approximately 50% improvement in creative problem-solving performance, measured using a standardized cognitive task (Remote Associates Test). The authors propose that reduced cognitive load, relief from directed attention fatigue, and sustained exposure to natural stimuli contribute to rapid improvements in executive cognition.

2. Cognitive Restoration Through Reduced Directed Attention Demand

Strayer, D. L., et al. (2015). Measuring the restorative effects of nature exposure using neurocognitive methods.

• Building on Attention Restoration Theory, this body of research shows that sustained exposure to natural environments reduces prefrontal attentional fatigue and improves executive function, working memory, and cognitive flexibility. Rather than increasing neural activation globally, nature exposure appears to support more efficient allocation of cognitive resources by shifting the brain away from constant directed attention demands.

3. Environmental Enrichment, Learning Capacity, and Implicit Behavior Change

Kempermann, G. (2019). Environmental enrichment, new neurons, and the neurobiology of individuality. Nature Reviews Neuroscience, 20, 235–245.

Authoritative review describing how enriched environments promote experience-dependent neuroplasticity, learning capacity, and behavioral adaptability through sustained interaction and sensory complexity. While much of the evidence is preclinical, the mechanisms identified—reduced stress signaling, enhanced exploratory behavior, and increased cognitive flexibility—provide a biological framework for understanding how complex environments can support durable changes in learning and behavior over time.

Orr, N., et al. (2016). How environmental contexts shape health behavior: A systematic review. Health & Place, 38, 1–12.

Systematic review demonstrating that environmental context strongly influences health-related behaviors—including movement patterns, stress coping, and daily routines—through implicit, habitual mechanisms rather than conscious decision-making. The findings support the idea that well-designed environments can scaffold lasting behavior change by shaping defaults and reducing cognitive friction.

Berman, M. G., Jonides, J., & Kaplan, S. (2008). The cognitive benefits of interacting with nature. Psychological Science, 19(12), 1207–1212.

Experimental study showing that interaction with natural environments improves attention and working memory performance compared to urban settings, supporting the view that restored executive function creates the cognitive conditions necessary for learning, flexibility, and downstream behavioral change.

Large-scale epidemiological and public health research consistently demonstrates that exposure to green environments is associated with reduced risk of chronic disease and premature mortality. Unlike short-term or activity-specific interventions, greenspace exposure reflects ambient, cumulative environmental influence—shaping daily stress levels, movement patterns, metabolic regulation, and cardiovascular risk over time. This body of evidence provides critical context for understanding why living and spending time in nature may support long-term health and disease prevention at the population level.

1. Greenspace Exposure and All-Cause & Cardiovascular Mortality

Twohig-Bennett, C., & Jones, A. (2018). The health benefits of the great outdoors: A systematic review and meta-analysis of greenspace exposure and health outcomes. Environmental Research, 166, 628–637.

• Systematic review and meta-analysis of 143 studies demonstrating that higher levels of greenspace exposure are associated with reductions in salivary cortisol, heart rate, and blood pressure, as well as lower risk of type II diabetes, all-cause mortality, and cardiovascular mortality. This work represents one of the most comprehensive syntheses linking natural environments to clinically relevant chronic disease outcomes.

2. Nature Exposure and Multi-Domain Health Outcomes (Narrative Review)

James, P., Hart, J. E., Banay, R. F., & Laden, F. (2021). Associations between Nature Exposure and Health: A Review of the Evidence. International Journal of Environmental Research and Public Health, 18(9), 4790.

• Narrative review summarizing epidemiological and mechanistic research showing consistent associations between nature exposure and improved cardiometabolic health, mental health, cognitive function, physical activity, and sleep. The review highlights the role of nature exposure as a contextual determinant of health rather than a discrete therapeutic intervention.

A broad body of research indicates that exposure to natural environments is associated with improvements in mental health, emotional regulation, and cognitive performance. While gardening represents one form of nature engagement, this section captures findings related to nature exposure more generally, including passive and short-term interactions.

1. Acute Mental Health Benefits of Urban Nature

Capaldi, C. A., Dopko, R. L., & Zelenski, J. M. (2025). Acute mental health benefits of urban nature. Nature Cities.

• Meta-analysis of 78 field experiments demonstrating that exposure to urban natural environments reduces depression and anxiety while enhancing overall mental well-being.

2. Short-Term Nature Exposure and Mood Regulation

Roberts, H., van Lissa, C., Hagedoorn, P., Kellar, I., & Helbich, M. (2019).The effect of short-term exposure to the natural environment on depressive mood: A systematic review and meta-analysis. arXiv.

• Meta-analysis indicating significant improvements in mood following brief exposure to natural environments, supporting the rapid psychological effects of nature contact.

3. Nature Exposure, Stress, and Cognitive Function

Denworth, L. (2024). Walks in Green Parks Mean Stronger Immune Systems and Better Mental Health.Scientific American.

• Synthesizes research linking time spent in green spaces with reductions in stress biomarkers, improvements in cognitive function, and enhanced mental health, providing an accessible overview of findings across multiple domains—including a large cohort finding better well-being with 120+ minutes/week in nature.

4. Nature Exposure and Mental Health as an Ecosystem Service

Bratman, G. N., Anderson, C. B., Berman, M. G., et al. (2019).
Nature and mental health: An ecosystem service perspective.
Science Advances, 5(7), eaax0903.

• Comprehensive review synthesizing experimental, epidemiological, and mechanistic evidence showing that exposure to natural environments is associated with improvements in mood, reductions in stress and rumination, and enhancements in cognitive function. The authors frame mental health benefits of nature as an ecosystem service, emphasizing relevance for prevention, resilience, and population-level mental well-being rather than clinical treatment alone.

1. Spontaneous Intensity and Perceived Effort During Outdoor Exercise

Gladwell, V. F., Brown, D. K., Wood, C., Sandercock, G. R. H., & Barton, J. L. (2013). The great outdoors: How a green exercise environment can benefit all. Extreme Physiology & Medicine, 2, 3.

Experimental and observational findings indicate that individuals exercising in outdoor green environments often select higher self‑paced intensities and report lower perceived exertion compared to indoor exercise, suggesting that natural settings may support greater spontaneous training stimulus without increased subjective effort.

2. Outdoor Exercise and Exercise Adherence

Thompson Coon, J., et al. (2011).Does participating in physical activity in outdoor natural environments have a greater effect on physical and mental wellbeing than physical activity indoors? A systematic review. Environmental Science & Technology, 45(5), 1761–1772.

• Systematic review comparing indoor versus outdoor physical activity, reporting greater feelings of revitalization, increased enjoyment, and stronger intention to repeat activity when exercise is performed outdoors, suggesting that natural environments may improve long-term exercise adherence and cumulative training exposure.

3. Cognitive and Affective Benefits of Walking in Nature

Berman, M. G., Jonides, J., & Kaplan, S. (2008). The cognitive benefits of interacting with nature.Psychological Science, 19(12), 1207–1212.

• Experimental study demonstrating that walking in natural environments improves attention and working memory performance and reduces mental fatigue compared to walking in urban environments, suggesting that outdoor movement may simultaneously support cognitive restoration and physical activity.

3. Green Exercise and Psychological Well-Being

Barton, J., & Pretty, J. (2010). What is the best dose of nature and green exercise for improving mental health?Environmental Science & Technology, 44(10), 3947–3955.

• Seminal study examining dose–response relationships between green exercise and mental health outcomes, showing that even short bouts of physical activity in natural environments are associated with improvements in mood and self-esteem, with implications for designing accessible, low-barrier movement practices.

5. Functional Movement, Terrain Variability, and Mobility Across the Lifespan

The strongest evidence for “functional movement” advantages outdoors comes from two complementary lines of research: (1) biomechanics comparing overground vs. treadmill locomotion, and (2) observational longevity research showing that long-lived populations often maintain high functional ability through frequent, terrain‑rich, outdoor movement embedded into daily life. Together, these bodies of evidence support the idea that natural environments can add proprioceptive, balance, and coordination demands that are under-stimulated on uniform indoor surfaces—and that this may matter most for mobility preservation with aging.

a. Overground vs. Treadmill Walking: Biomechanical and Perceptual Differences

Vickery-Howe, D. M., Bonanno, D. R., Dascombe, B. J., Drain, J. R., Clarke, A. C., Hoolihan, B., Willy, R. W., & Middleton, K. J. (2023). Physiological, perceptual, and biomechanical differences between treadmill and overground walking in healthy adults: A systematic review and meta-analysis. Journal of Sports Sciences, 41(23), 2088–2120.

• Systematic review and meta-analysis comparing treadmill vs. overground walking at matched speeds, reporting meaningful differences in spatiotemporal parameters (e.g., step/stride characteristics), kinetics, and oxygen cost. The authors interpret many treadmill‑specific changes as stability-related constraints and surface-specific mechanics, reinforcing that overground walking better represents the sensory and motor demands of real-world locomotion.

b. Terrain Variability: Neuromuscular Engagement and Stabilization Demands

Voloshina, A. S., & Ferris, D. P. (2015). Biomechanics and energetics of running on uneven terrain.Journal of Experimental Biology, 218, 711–719.

• Experimental study showing that uneven terrain increases stabilizing muscle activation and neuromuscular engagement to manage variability and perturbations, supporting the role of terrain-rich movement in coordination, joint control, and functional resilience rather than isolated performance outcomes.

c. Longevity Populations: Daily Outdoor Movement and Mobility Preservation

Ungvari, Z., Fazekas-Pongor, V., Csiszar, A., & Kunutsor, S. K. (2023). The multifaceted benefits of walking for healthy aging: from Blue Zones to molecular mechanisms. GeroScience, 45(6), 3211–3239.

• Comprehensive review synthesizing evidence that habitual walking and low-intensity movement support cardiometabolic health, cognitive function, sleep, and longevity. The authors explicitly connect these benefits to Blue Zone lifestyles, where walking and physically active daily living are embedded into routine life across the lifespan.

Herbert, C., House, M., Dietzman, R., Climstein, M., Furness, J., & Kemp-Smith, K. (2022). Blue Zones: Centenarian modes of physical activity: A scoping review. Journal of Population Ageing.

• Scoping review describing the predominant modes of physical activity reported in Blue Zone populations, highlighting outdoor and occupational movement patterns (e.g., agriculture, walking/hiking on uneven terrain, physically active daily routines) that are associated with high functional ability and autonomy in very old age.

Together, these findings support a practical longevity hypothesis: environments that naturally encourage frequent walking, outdoor time, and terrain variability may help preserve coordination, balance, and functional mobility longer into later years—largely through consistent real-world movement exposures rather than isolated “training sessions.”

7. Temperature Variability, Metabolic Flexibility, and Environmental Adaptation

Rather than focusing narrowly on extreme heat or cold exposure, a broader body of research examines how regular exposure to variable ambient temperatures influences metabolic health, cardiovascular regulation, and physiological resilience. These findings are relevant to outdoor movement and daily life, where temperature naturally fluctuates across seasons, times of day, and microclimates.

a. Ambient Temperature Exposure and Metabolic Health

Blondin, D. P., & Haman, F. (2018). Shivering and nonshivering thermogenesis in skeletal muscle. Journal of Applied Physiology, 124(2), 473–481.

Reviews evidence that mild cold exposure activates thermogenic pathways in skeletal muscle and brown adipose tissue, increasing energy expenditure and supporting metabolic flexibility without the need for extreme cold stress.

van Marken Lichtenbelt, W. D., et al. (2009). Cold-activated brown adipose tissue in healthy men. New England Journal of Medicine, 360, 1500–1508.

Landmark human study demonstrating that exposure to cooler environments activates brown adipose tissue, increasing glucose uptake and energy expenditure, suggesting a role for ambient temperature variability in metabolic regulation.

b. Temperature Variability and Cardiovascular & Autonomic Regulation

Hanna, J. M., & Brown, D. E. (1983). Human heat balance during rest and exercise. Annual Review of Anthropology, 12, 73–97.

Foundational review describing how regular exposure to varied thermal environments shapes cardiovascular responses, sweating efficiency, and autonomic regulation, supporting the idea that thermal variability contributes to physiological adaptability.

Research on gardening and therapeutic horticulture consistently demonstrates benefits across mental health, physical functioning, social connection, and quality of life. Importantly, many of these outcomes overlap with findings from broader nature exposure research, particularly in the domains of mental health, stress regulation, and cognitive function. This section therefore focuses on what is distinctive about gardening specifically: active engagement with living systems, purposeful movement, skill-building, food production, and sustained interaction over time.

1. Gardening and Global Health Outcomes

Soga, M., Gaston, K. J., & Yamaura, Y. (2017). Gardening is beneficial for health: A meta-analysis. Preventive Medicine Reports, 5, 92–99.

• Comprehensive meta-analysis showing that gardening is associated with reduced depression and anxiety, lower body mass index, increased life satisfaction, enhanced social cohesion, and improved overall physical and mental health, supporting gardening as a multi-domain health-promoting activity.

2. Gardening, Well-Being, and Quality of Life

Panțiru I, Ronaldson A, Sima N, Dregan A, Sima R. (2024). The Impact of Gardening on Well-Being, Mental Health, and Quality of Life: An Umbrella Review and Meta-Analysis. Systematic Reviews, 13, Article 125.

• Umbrella review synthesizing findings from 40 studies, demonstrating consistent positive effects of gardening and horticultural therapy on mental well-being, stress reduction, and quality of life across general and vulnerable populations.

3. Therapeutic Horticulture Under High Psychological Stress and Chronic Physiological Dysregulation

These studies examine horticultural therapy in clinical settings characterized by high psychological stress and symptom burden. While conducted in psychiatric populations, they are included here to illustrate the potential robustness of gardening-based interventions under conditions of significant physiological and emotional strain.

Zhang, X., et al. (2024). Impact of horticultural therapy on patients admitted to psychiatric wards: A randomized controlled trial. Scientific Reports, 14.

• Randomized controlled trial showing that structured horticultural therapy significantly reduces anxiety and depressive symptoms in psychiatric inpatients, illustrating the therapeutic potential of gardening-based interventions in clinical contexts.

Zhang, L., Zhao, Y., Liu, J., Xu, F., & Wang, Z. (2021). Effectiveness of Horticultural Therapy in People with Schizophrenia: A Systematic Review and Meta-Analysis. International Journal of Environmental Research and Public Health, 18(3), 964.

• Systematic review and meta-analysis demonstrating that horticultural therapy improves psychosocial and psychological symptoms in individuals with schizophrenia, supporting the applicability of garden-based interventions beyond general wellness settings.

4. Gardening, Aging, and Functional Capacity

Wang, D., & MacMillan, T. (2013). The benefits of gardening for older adults: A systematic review of the literature.Activities, Adaptation & Aging, 37(2), 153–181.

• Foundational review showing that gardening supports physical activity, mobility, fine and gross motor skills, functional independence, and psychological well-being in older adults.

Genter, C., Roberts, A., Richardson, J., & Sheaff, M. (2015). The wellbeing benefits of gardening for older adults in residential care homes. Ageing & Society, 35(8), 1834–1856.

• Study demonstrating that gardening participation in residential care settings enhances life satisfaction, social engagement, and mental health, highlighting the social and functional dimensions of gardening in later life.

5. Healthcare and Institutional Garden Environments

Atypon. (2024). Implementation and Impact of Health Care Gardens: A Systematic Scoping Review. PubMed.

• Scoping review showing that garden interventions in healthcare settings positively impact stress levels, quality of life, cognitive function, physical activity, and dietary behaviors among patients, visitors, and staff.

Endocrine and immune research suggests that exposure to natural environments may influence stress hormone regulation, immune activity, and recovery processes. Rather than acting through direct treatment effects, nature-based exposures appear to modulate upstream regulatory systems—particularly the hypothalamic–pituitary–adrenal (HPA) axis, autonomic nervous system signaling, and inflammatory pathways—providing context for observed associations with stress resilience, immune competence, and overall physiological balance.

1. Forest Bathing & Immune Function (NK Cells and Cytokines)

Li, Q., Morimoto, K., Kobayashi, M., et al. (2008). Effect of forest bathing trips on human immune function. International Journal of Immunopathology and Pharmacology, 21(1), 117–127.

• Demonstrates that time spent in forest environments is associated with increased natural killer (NK) cell activity and elevated expression of anti-cancer proteins, with effects persisting for days to weeks. The findings suggest that nature exposure may influence immune readiness through stress reduction and biochemical signaling rather than physical exercise alone.

2. Stress Reduction and Immune Modulation (HPA–Immune Coupling)

Segerstrom, S. C., & Miller, G. E. (2004). Psychological stress and the human immune system: A meta-analytic study. Psychological Bulletin, 130(4), 601–630.

• Large meta-analysis showing that chronic psychological stress suppresses multiple aspects of cellular and humoral immunity, while acute stress responses may transiently enhance certain immune functions. This work provides a mechanistic framework for understanding how stress-reducing environments may indirectly support immune resilience.

3. Autonomic–Immune Coupling (The Inflammatory Reflex)

Tracey, K. J. (2002). The inflammatory reflex. Nature, 420, 853–859.

• Establishes the vagus nerve as a key regulator of inflammatory responses, demonstrating that autonomic nervous system activity can directly influence immune signaling. This foundational work supports the plausibility that environments promoting parasympathetic activation may contribute to reduced inflammatory burden.

4. Inflammation and Nature Exposure

Kondo, M. C., Fluehr, J. M., McKeon, T., & Branas, C. C. (2018). Nature-based interventions for improving health and well-being: A systematic review. International Journal of Environmental Research and Public Health, 15(4), 806.

• Systematic review examining nature-based interventions and health outcomes, including markers related to stress, inflammation, and immune function. The review highlights consistent associations between exposure to green environments and reductions in physiological stress and inflammatory risk, while emphasizing the need for further controlled research.

5. Neuroendocrine Stress Recovery Through Gardening

Van den Berg, A. E., Koole, S. L., & van der Wulp, N. Y. (2007). Gardening promotes neuroendocrine and affective restoration from stress. Journal of Health Psychology, 12(2), 215–223.

• Experimental study showing that active engagement in gardening following a stressor leads to greater reductions in cortisol levels and improved mood compared to indoor reading tasks, supporting the role of nature-based activity in facilitating neuroendocrine recovery.

6. Circadian Alignment and Immune Resilience in Outdoor Environments

Denworth, L. (2024). Walks in Green Parks Mean Stronger Immune Systems and Better Mental Health. Scientific American.

• Summarizes research linking outdoor light exposure and time spent in green spaces with improved circadian regulation, sleep quality, and downstream immune resilience, illustrating the interconnected nature of endocrine, circadian, and immune systems.

Environmental and microbiome research suggests that regular contact with biodiverse natural environments may play a role in immune regulation and long-term health. Rather than acting through a single pathway, these effects are thought to emerge from interactions between environmental microbial diversity, human microbiota composition, and immune system training. This area of research is active and evolving, but it provides important context for understanding why ecological interaction may matter for resilience and disease risk.

1. Biodiversity Hypothesis / Immune Training

Rook, G. A. W. (2013). A biodiversity hypothesis. PubMed.

Introduces the foundational hypothesis that reduced exposure to environmental microbes in modern lifestyles may impair immune regulation, contributing to inflammatory and autoimmune conditions, and proposes that contact with biodiverse environments supports immune balance through microbiome-mediated mechanisms.

2. Soil–Plant–Human Microbiome Continuum

Wu, Y., Deng, Y., & He, Z. (2025). The soil–plant–human gut microbiome axis into perspective. Nature Communications.

Presents a systems-level framework describing how soil and plant microbial communities may influence human microbiota through environmental contact and food systems, offering biological plausibility for nature-based influences on immune and metabolic health.

3. Gardening, Microbial Exposure, and Immune Markers

University of Helsinki Research (2024). Urban gardening may improve human health via microbial exposure. Science Advances, 6(42), eaba2578.

Reports that gardening with microbially diverse soil environments is associated with increased human microbiota diversity and changes in immune-related biomarkers, supporting the concept that hands-on interaction with living soils may contribute to immune training.

4. Residential Greenness and Human Microbiota

Li, Q., et al. (2023). Association between residential greenness and human microbiota. Environmental Health Perspectives, 131(8).

Provides population-level evidence linking exposure to greener residential environments with differences in human gut microbiota composition, suggesting that everyday environmental context may shape microbial profiles relevant to health.

5. Greenspace and Microbiota Diversity (Systematic Review)

Zhu, Y., et al. (2024). Greenspace and human microbiota: A systematic review. Systematic Reviews, 13, Article 125.

Synthesizes findings across multiple studies showing consistent associations between greenspace exposure and increased gut and skin microbiota diversity, while emphasizing the need for further research to clarify causality and mechanisms.

Evolutionary and environmental health research suggests that many aspects of modern life differ markedly from the conditions under which human physiology evolved. This mismatch provides context for why exposure to natural environments, including sensory complexity and ecological interaction, may support health and resilience.

1. Evolutionary Mismatch / Environmental Mismatch

Lieberman, D. E. (2013). The Story of the Human Body: Evolution, Health, and Disease. Harvard University Press.

• Explores how many modern chronic diseases emerge from a mismatch between contemporary lifestyles (sedentary behavior, indoor living, ultra-processed diets) and the conditions under which human physiology evolved, providing an evolutionary framework for understanding why movement, environmental exposure, and natural rhythms appear to support long-term health.

2. Biophilia Hypothesis

Wilson, E. O. (1984). Biophilia. Harvard University Press.

• Proposes that humans possess an innate biological affinity for natural environments shaped by evolutionary history, offering a theoretical basis for why interaction with living systems may influence psychological well-being, stress regulation, and behavioral preference.

3. Environmental Psychology & Evolutionary Preference

Kaplan, R., & Kaplan, S. (1989). The Experience of Nature: A Psychological Perspective. Cambridge University Press.

• Proposes Attention Restoration Theory, suggesting that natural environments align with evolved cognitive processing patterns, allowing the brain to recover from directed attention fatigue and mental overload common in modern, built environments.

4. Nature, Health, and Evolutionary Plausibility

Frumkin, H., et al. (2017). Nature Contact and Human Health: A Research Agenda. American Journal of Preventive Medicine.

• Reviews evidence linking nature contact to multiple health outcomes and explicitly discusses evolutionary plausibility as a framework for interpreting these associations, emphasizing that human biology developed in close interaction with natural environments rich in movement, sensory input, and ecological complexity.

5. Evolutionary Medicine

Gluckman, P., & Hanson, M. (2006). Mismatch: Why Our World No Longer Fits Our Bodies. Oxford University Press.

• Describes how rapid environmental change has outpaced biological adaptation, contributing to increased vulnerability to metabolic, cardiovascular, and inflammatory diseases, and provides a systems-level explanation for why reintroducing evolutionarily familiar exposures may support resilience and healthspan.