Nature Nurtures: Evidence for Nature’s Impact on Mental Well-Being

SPECIAL REPORT: LIFESTYLE PSYCHIATRY

A Breath of Air

In spring 2002, Jonathan Dosick was hospitalized at an inpatient psychiatric facility in Massachusetts. The days could feel long, and the unit, like so many, was often “sterile and boring.” What made a difference were the small freedoms: stepping outside for a walk or sitting down with a hot chocolate at the local coffee shop. “I really appreciated that,” he recalls, “because it helped me feel connected to the world outside. The cold, fresh air can be bracing. Going outside can help you reconnect with what’s out there; it is a bridge back to the outside world.”¹ Not long after his discharge, Jonathan learned that the hospital had stopped letting patients go outside at all, citing concerns about elopement. Having just experienced firsthand how vital those moments of fresh air could be, he thought to himself, "That’s not right." This marked the beginning of his work as a peer advocate and a wider conversation about the essential role of nature in psychiatric care.

From Intuition to Evidence

Across cultures and throughout history, people have turned to nature for comfort, healing, and perspective. Only recently, however, researchers have begun to quantify just how powerful time in green space can be for supporting mental health, showing links to lower stress, improved mood, and even reduced psychiatric symptoms. These benefits appear to arise through multiple pathways: reducing exposure to pollutants, encouraging healthier and prosocial routines, and buffering the stress response. It is therefore imperative to explore the science and stories that illustrate these effects and to address the challenges of ensuring equitable access to outdoor spaces. Recommendations should therefore weave nature into mental health care—from lifestyle choices to clinical augmentation of established treatment practices to the development of supportive national policies.

Hippocrates, the proverbial father of medicine, is widely credited with the saying that “nature itself is the best physician,” reflecting his belief in the environment’s capacity to heal.² Enlightenment thinkers retreated to gardens and forests seeking tranquility, whereas early 20th-century sanitariums prescribed fresh air and open landscapes as treatment for tuberculosis. For centuries, humans have intuitively turned to the natural world for restoration. What distinguishes the present moment is the mounting body of scientific evidence validating that intuition. Advances in epidemiology, neuroscience, and experimental design allow us to examine how access to green space influences mental health.

Green space is defined broadly, which has historically limited consistent understanding across disciplines and geographic regions.³ It can include public parks, gardens, tree-lined streets, natural views from windows, and even indoor plants. Although green space dominates the literature, it is important to recognize that blue spaces, such as rivers, lakes, and seascapes, are also associated with improved well-being. ⁴

Over the past 35 years, research examining green space and mental well-being has expanded rapidly. A 2020 bibliometric analysis showed that the number of observational and experimental studies increased sharply after 2000, reflecting the field’s growing recognition.⁵ A later 2024 review in Nature synthesized 41 studies focusing on the impact of green space on the mental health of disadvantaged populations. Of those studies, 70% found that neighborhood green space exerted a protective effect on mental health, with outcomes including greater life satisfaction, reduced depression, and improved emotional well-being—even when controlling for socioeconomic status.⁶ These findings are particularly significant because access to green space has historically been shaped by racist and classist policies such as redlining, underscoring that equitable access is both a mental health and an environmental justice issue.⁷ The COVID-19 pandemic offered an unfortunate natural experiment that further reinforced these inequities. During periods of lockdown, individuals with higher amounts of green space in their zip codes reported lower rates of depression, anxiety, and COVID-19–specific worries compared with those with less access to green space.⁸ This stark contrast underscored how access to nature is not merely a lifestyle preference but a determinant of mental health resilience during times of crisis.

In addition to general mental well-being, green space has an association with the development of specific psychiatric disorders. One of the most compelling studies comes from Denmark, where researchers tracked nearly 1 million individuals born between 1985 and 2003, quantifying green space exposure around their childhood homes. In a dose-dependent relationship, lower levels of green space in childhood were associated with a 15% to 55% increased risk of developing psychiatric disorders later in life (including mood, schizophrenia spectrum, and substance use disorders), even after adjusting for urbanicity, socioeconomic status, and family psychiatric history.⁹ This suggests that green space exposure during early development may be important for mental health across our lifetimes.

Of course, much of this evidence is observational. To establish causality, randomized controlled trials are essential, and here, too, the data are compelling. In Philadelphia, Pennsylvania, Eugenia C. South, MD, MSHP, and colleagues randomly assigned more than 500 vacant lots into several treatment groups, including a greening intervention that involved removing trash, grading the land, and planting grass and trees, vs a control group with no intervention at all. Residents living near fully greened lots reported significant decreases in feelings of depression and worthlessness compared with controls.¹⁰ These results demonstrate not only that green space promotes mental health, but also that urban greening interventions are feasible, scalable, and capable of addressing mental health disparities in urban communities.

How Nature Heals

Why does green space matter for mental health? Researchers have proposed 3 broad mechanisms: harm mitigation, encouragement of healthy behaviors, and psychological restoration.¹¹

In terms of harm mitigation, green space buffers exposure to air pollution, noise, and heat—all of which disproportionately affect vulnerable groups and can impact cognitive development.¹¹ With respect to healthy behaviors, natural settings encourage physical activity and social interaction, providing both physical benefits and social coping strategies. Finally, psychological restoration may be the most direct mechanism by which green space impacts mental health (though it remains an active area of study). Studies suggest that exposure to natural environments impacts brain circuits involved in attention restoration, stress reduction, and rumination.¹² For example, one experiment found that individuals who took a 90-minute walk in nature showed decreased activation in the subgenual prefrontal cortex, a region associated with maladaptive rumination, whereas those who walked in urban settings did not.¹³

At the same time, the absence of green space—or the presence of urban stressors—appears to shape neural development in measurable ways. Functional neuroimaging studies of individuals with urban upbringings show heightened amygdala activity during stress and altered connectivity in the anterior cingulate cortex, both of which are critical regulators of the limbic stress response.¹⁴ These findings reinforce that exposure to natural vs urban environments may leave lasting imprints on brain structures tied to emotional regulation, but more studies are needed to unpack these effects.

Beyond these established mechanisms, researchers are beginning to uncover additional ways the natural world may influence mental health. For example, emerging research shows that spending time in nature can alter the gut microbiome in ways that meaningfully affect mental well-being.¹⁵ Even exposure to bird sounds has been shown to exert protective effects on anxiety and paranoia.¹⁶ These findings highlight how much there is still to learn about the subtle but powerful ways nature supports our mental health.

Taken together, the evidence is striking. From Hippocrates’ early observations to modern neuroimaging, the data converge on a central truth: Nature matters for mental health. Green space access is not merely an aesthetic or recreational amenity but can be a meaningful determinant of psychiatric well-being.

Translating Evidence Into Practice

The growing body of evidence demonstrating the positive relationship between nature and mental health has already started to influence the health care system. Mental health professionals and hospitals have started to integrate green space therapeutics into care. These interventions should be framed as additions to our therapeutic tool kit: powerful but complementary to the established practices of psychotherapy and psychopharmacology.

At its most basic, green exposure therapy involves getting people outdoors, often through group walks in natural settings. A 2023 review of 16 studies found that such walks improved mood, optimism, and overall well-being, with significantly greater benefits in natural vs urban environments.¹⁷ Horticultural therapy, which uses gardening and plant-based activities as a therapeutic medium, also has a large body of evidence. A 2022 meta-analysis of 18 randomized controlled trials demonstrated significant reductions in general measures of mental health.¹⁸ Finally, Shinrin-yoku, or forest bathing, a Japanese practice of mindful immersion in nature, has been associated with improvements in mood disorders. Early randomized controlled trials provide positive evidence supporting its role as an adjuvant to psychotropic medication.¹⁹ Taken together, these emerging approaches highlight the diverse ways nature-based interventions can augment traditional psychiatric care.

In the outpatient clinical setting, some clinicians are weaving these practices into routine care. One widely adopted strategy is the nature prescription, a nonpharmacological recommendation that directs patients to spend time in parks or other natural settings. Rooted in the tradition of nonmedical prescriptions for exercise, nature prescriptions extend this model to environmental exposures, encouraging restorative time outdoors. More than 100 park prescription programs now exist across the United States, supported by organizations such as the National ParkRx Initiative and Park Rx America.²⁰ Grassroots programs like Walk With a Doc take this concept further, facilitating physician-patient walks in community parks.²¹ Although formal evidence for these initiatives is limited, and more studies are needed to assess the impacts, anecdotal experiences highlight the restorative value of fresh air, movement, and social connection.

The availability of fresh air and natural environments has been shown to be just as crucial to patient mental health inside the hospital as it is outside the hospital. Started by the wonderful work of Dosick, in Massachusetts, a bill was drafted and sponsored by former state representative Denise Provost and Senator Patricia Jehlen to add “daily access to fresh air and the outdoors” to the preexisting fundamental rights in the Massachusetts Department of Mental Health licensing codes (adding to access to phones, mail, visitors, privacy and dignity, and legal counsel). It was initially filed in 2005 and, after 5 legislative sessions, finally passed a decade later on Governor Deval Patrick’s last day in office in 2015.²²

As advocacy for the implementation of this policy continues, hospital systems are developing creative solutions for biophilic design and incorporating natural environments into inpatient behavioral health settings, such as through nature art.^23,24 One initiative is underway at Brigham and Women’s Faulkner Hospital in Boston, Massachusetts. After construction blocked patient views of nearby trees and green space, a team, led by Christopher AhnAllen, PhD; Sarah Kovan, MD; and Jeremy Wortzel, MD, partnered with the Osher Center for Integrative Medicine to install immersive nature photography throughout the psychiatric unit (Figure). Vinyl installations of tree canopies, lakes, and forest scenes replaced blank white walls, and the team is now studying the impact of these interventions on patient well-being. This project highlights a broader movement: When outdoor access is limited, bringing nature indoors can still provide meaningful therapeutic benefit.

Yet despite this growing body of evidence, challenges remain. Access to green space is still deeply unequal across communities, with marginalized groups often facing the greatest barriers. In inpatient psychiatric units, concerns about safety, staffing, and resources frequently limit opportunities to go outdoors.²⁵ Creating safe therapeutic spaces requires funding not only for infrastructure but also for adequate staffing to ensure patient well-being. Although some local legislation has begun to address outdoor access in psychiatric settings, we still lack effective, nationally standardized, and enforceable policies that guarantee safe, equitable green space access for all patients.

Recommendations for Clinical Practice

Moving forward, several recommendations can help bridge this gap. These strategies should be understood as augmentation tools—creative ways of broadening psychiatric care while always remaining grounded in our core evidence-based practices of psychotherapy and psychopharmacology. At the lifestyle level, clinicians can encourage patients to spend time outdoors and to incorporate restorative natural experiences into daily routines. In outpatient care, nature prescriptions, outdoor therapy groups, and walking groups may help patients engage with the mental health benefits of green space. For inpatient settings, dedicating more resources toward outdoor time or integrating nature into the unit through artwork and indoor greenery can begin to transform sterile units into more therapeutic environments. On a broader scale, advocacy for national legislation is crucial to ensure green space becomes a standardized, enforced, safe, and well-resourced component of psychiatric care, guaranteeing that every person, regardless of where they live or are treated, has access to the healing power of nature. Integrating nature into mental health care represents an emerging frontier—one grounded in both empirical evidence and the moral pursuit of holistic healing.

Dr Wortzel is a chief resident at Mass General Brigham – Brigham and Women’s Hospital/Harvard Medical School. Dr Hondros-McCarthy is a child, adolescent and adult psychiatrist in an integrated behavioral health position within a pediatric practice through Tufts Medical Center. Dr Kovan is a chief psychiatry resident at Brigham and Women’s Hospital/Harvard Medical School. Dr Peng is currently an inpatient psychiatrist at McLean Hospital.

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