How Nature Walks Support Mental Health After Limb Loss
Reading Time: 6 minutes
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Summary:
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Harvard research links green space to 12% lower mortality and measurably reduced depression
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Mental health—not exercise—was the strongest factor explaining the effect
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Forest therapy activates the parasympathetic nervous system and lowers cortisol
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Twenty minutes in nature three times a week is enough to see a benefit
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For the limb loss community, where depression is common post-amputation, the evidence is directly relevant
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A few years ago, forest bathing dominated wellness headlines for its physiological and psychological benefits. Recently, it may have been rebranded playfully as “touching grass” or nature walks, but the premise is the same: walking a trail, sitting in a park, being near trees, or simply looking at any greenery has been associated with a sense of calm. And some doctors are already writing it into their treatment plans.
For people in the limb loss community, the relevance is direct. Mental health challenges, like depression, anxiety, and grief, following amputation, are common and well-documented. And the research on nature and mental health offers one accessible, low-cost tool that may complement existing care.
What the Research Shows
One of the most cited lines of evidence comes from the Nurses’ Health Study, a long-running cohort study that has tracked more than 121,000 women over several decades. Peter James, an associate professor of population medicine at Harvard Medical School’s affiliated Harvard Pilgrim Health Care Institute, used the study’s data to examine the relationship between green space and health outcomes.
Pairing medical records with satellite imagery, James and colleagues found that women living in areas with the highest levels of green space were 12% less likely to die during an eight-year follow-up period. The association was strongest for cancer and respiratory mortality, as described in a 2016 paper published in Environmental Health Perspectives.
Notably, when the researchers analyzed the mechanisms behind this finding, physical activity and air quality alone didn’t account for the difference. The most significant factor was mental health, which was measured by rates of diagnosed depression and antidepressant use. Social engagement played a secondary but meaningful role.
Why Green Space Affects the Brain
Other studies have pointed to measurable physiological changes when people spend time in natural environments. Research has found lower levels of salivary cortisol—a biological marker of stress—among people who spent time in nature compared to those who remained in urban or built environments. Separate work has found reduced activity in brain regions associated with rumination, the cycle of repetitive negative thinking.
Even partial exposure appears to help. Studies have linked views of nature through windows and the presence of indoor plants to cognitive benefits, suggesting the effect isn’t limited to outdoor activity.
James, who has continued researching the specific elements of green space—the proportion of trees, flowers, or grass in a given area—that most influence outcomes, puts it simply: humans did not evolve for windowless rooms and artificial environments. Exposure to nature, in his view, is not a luxury; it’s a return to baseline.
Forest Therapy and the Nervous System
Susan Abookire, an assistant professor of medicine at Brigham and Women’s Hospital affiliated with Harvard Medical School, has brought this research into practice through the forest therapy mentioned above, also known as shinrin-yoku—a Japanese therapeutic practice involving deliberate, mindful time in a forest setting. The Japanese government began promoting the practice in the 1980s, and since then, hundreds of studies have examined its effects on mental health.
Abookire, who holds a certification in forest therapy, leads monthly outings for medical residents at Harvard University’s Arnold Arboretum in Boston. Participants are guided to engage their senses—noticing smells, sounds, and textures—rather than focus on physical activity.
The physiological explanation, according to Abookire, involves the autonomic nervous system. Time in nature activates the parasympathetic nervous system (sometimes described as the “rest and digest” mode) and quiets the sympathetic response associated with stress and mental effort. Forest environments also emit aromatic compounds that research has linked to immune function, and soil exposure has been associated with effects on gut microbiome health.
You Don’t Need a Literal Forest
The good news is that research has shown that access to wilderness isn’t required. Abookire notes that a city park or a small patch of grass can produce similar effects, provided two conditions are met: a sense of mental separation from everyday demands and a natural element to direct attention toward.
A 2019 study published in Frontiers in Psychology found that flexible, self-directed “nature time”—participants chose their own location, timing, and duration—produced lower cortisol levels after as little as 20 minutes of exposure three times per week.
James echoes this point. The goal, in his view, is not a trip to a national park but regular contact with green space built into ordinary life. He has argued that urban planning and policy play a role in making that access equitable, noting that lower-income neighborhoods stand to benefit most from increased green space and currently have the least.
California physician Daphne Miller, who practices in North Richmond—one of the lowest per-capita green space communities in the San Francisco Bay Area—writes formal nature prescriptions for patients dealing with grief, depression, and anxiety. A typical prescription specifies a location, duration, and frequency, in the same format as a medication script.
The Bottom Line
The evidence connecting time in nature to better mental health has become substantial enough that some physicians now treat green space as a clinical tool. The underlying mechanisms—reduced stress hormones, shifts in nervous system activity, and lower rates of depression—are increasingly well supported. For the limb loss community, where mental health challenges are common in both the short- and long-term periods after amputation, that research is directly relevant.
While access isn’t equal, and individual circumstances vary, the core finding is straightforward: for many people, going outside helps.
Related Reading:
Why Meditation Walking is Great for Your Health
