Evidence that nature can improve mental health and wellbeing has been germinating slowly but surely.
To give it roots, researchers have developed a conceptual model to help inform decisions about including greenery in urban environments.
Their paper, published in the journal Science Advances, includes a consensus statement about the mental health benefits of nature from more than two dozen experts in natural, social and health sciences, including architecture, psychology, public health, and medicine.
“For millennia, many different cultures, traditions, and religious and spiritual practices have spoken directly to our deep relationship with nature,” says lead author Gregory Bratman from the University of Washington, US.
“And more recently, … evidence has been steadily gathering in this emerging, interdisciplinary field.”
Yet many city areas are nature deprived, he adds, and people’s access is dwindling due to growing urbanisation, compounded by modern lifestyles.
Concurrently, years lived with disability from mental illness now constitutes a third of the global burden of disease – on par with heart disease and stroke.
The authors reviewed multi-level evidence that supports links between nature and psychological wellbeing, including positive states, a sense of meaning and purpose, cognition, imagination and creativity.
“In hundreds of studies, nature experience is associated with increased happiness, social engagement, and manageability of life tasks, and decreased mental distress,” says senior author Gretchen Daily from Stanford University, US.
Natural environments also improve sleep and reduce stress, both key risk factors for mental illness – particularly depression, the leading cause of disability worldwide.
Although these all have other contributing influences, research hints at connections between low nature exposure and other mental illnesses as well, including anxiety and attention deficit hyperactivity disorder.
This body of research, which the authors write should soon allow meaningful, accurate predictions about environmental impacts on mental health, formed a basis for their model.
Given the best available evidence, the model itself draws from other ecosystem service models. In an elaborate stepwise fashion, it factors in natural features that promote mental health, people’s dose and exposure and the resulting psychological benefits.
The framework aims to help stakeholders such as city planners, landscape architects, developers, engineers and community organisations evaluate the psychological impacts of decisions that impact the environment.
The authors hope this will inform planning, funding, and development of public spaces, and improve mental health equity in deprived communities.
Similar efforts are already being made to improve general health, they note, such as urban tree canopies to enhance air quality, structuring parks to increase physical activity, and addressing health disparities by targeting poorer neighbourhoods.
Research on mental health impacts of nature is still emerging, Bratman acknowledges, saying that studies still need to clarify causal mechanisms and build a more thorough evidence base.
“For example,” he says, “more work needs to be done regarding questions about how and whether different types of nature impact different people differently.”
As the evidence grows, the model can be developed along with it. But it is critical to start somewhere, the authors argue.
“The repercussions of these choices on mental health may add up to be quite significant on a population level,” they write, “and a framework is needed for their consideration and integration into decision-making today that will have an influence in the decades to come.”
