access. Others have experienced trauma outdoors, or may feel unwelcome or unsafe.
But Tandon believes these barriers are surmountable— and though it may look different for each person, we all deserve to enjoy the outdoors. Even a short walk each day can reap big rewards for our health.
“ There is a way that being in nature is possible for everyone,” she says.
Though promoting nature exposure for human health has gained momentum in recent years, there’ s a certain obvious logic to this connection, says Mariah Stump, MD, MPH, a primary care physician in Rhode Island.
“ The outdoor world, historically, as human beings— that’ s our natural environment,” says Stump, who’ s also the director of the Medical School’ s scholarly concentration on Lifestyle Medicine and Integrative Health. In nature,“ we’ re using different parts of our brain. And it’ s a very ancient part, because we’ re anciently wired for that. But we’ ve tuned all of that out, because we’ re so tuned into our devices.”
Christopher Moore, PhD, the associate director of Brown’ s Carney Institute for Brain Science, agrees.“ Our brains were made to respond optimally to certain kinds of stimuli in the world we evolved [ in ],” he says. Mammalian brains release dopamine, sometimes called the“ feel-good” chemical, in response to basic biological triggers: eating, spotting a potential mate— even just looking at nature.“ Dopamine systems are triggered when you see natural scenes,” Moore says.
For decades researchers have observed the small but measurable therapeutic effects of nature for hospital patients, such as shorter hospital stays and reduced pain medication usage in surgical patients who could see trees out their window, instead of a brick wall, according to a 1984 paper in Science. More broadly, nature exposure— which includes not only physical immersion in natural areas but even photographs and virtual reality— correlates in study after study with better sleep, fewer PTSD and ADHD symptoms, and lower rates of stress, anxiety, and depression. Other studies have found that young children who play outside have considerably lower rates of myopia.
Meanwhile practitioners of forest bathing— the centuriesold practice of immersing oneself in the woods to improve well-being— have significantly more natural killer cells,
“ In nature, we’ re using different parts of our brain. But we’ ve tuned all of that out, because we’ re so tuned into our devices.”
which play key roles in our immune systems; the effects lasted for days or weeks afterwards. This may be due to antimicrobial volatile compounds emitted by plants called phytoncides, which have been used in traditional medicine around the world for centuries. Phytoncides are now a hot area of research, with evidence of beneficial effects ranging from lower stress and anxiety to tumor suppression.
Moore, a neuroscientist, studies rodents to understand how the systems of the body, both neural and non-neural, work together to perceive the world. By modestly enriching lab mice enclosures— allowing them to touch and explore freely, interact with other mice, even face some minor challenges— he and his team observed“ dramatic transformations” in their brains, including new synapses and blood vessels. The stimulation of dopamine axons briefly opens the blood-brain barrier, which seems to help with learning and lets the brain clear out waste.
“ It’ s not subtle,” Moore says of the brain changes.“ To be clear, we didn’ t do much” in terms of changing the environment— the mice were still in lab enclosures. Yet he believes their studies suggest that our brains are optimized in a naturalistic, complex world. There is“ something rich and interesting about natural environments for our health. And it’ s not just something; there are endless dimensions of this,” Moore says.
Stump notes that until a couple of centuries ago, most people lived in rural areas, and worked and spent most of their time outdoors. Now more than half of the world’ s population lives in cities; the average American spends
12 HEALTH DISCOVERIES @ BROWN l SPRING 2026