Pooja Tandon ’96 MD’99, MPH, can still vividly recall the day more than 10 years ago that transformed her research on child health.
A pediatrician and University of Washington professor in Seattle, she had brought her boys, who were 2 and 5 at the time, for a day at the beach. As they dug intently in the sand for hours, Tandon dug into her book, Last Child in the Woods, in which author Richard Louv coins the term “nature-deficit disorder” to describe how our society’s decreasing exposure to the outdoors harms children and all of us.
As she read—without interruption, for the first time in years—Tandon thought back to the times her sons and other kids would act out after too much time inside, yet they behaved and played nicely when they could go outside and “move their little bodies.” She remembered her very urban upbringing in Lucknow, India, where she nevertheless spent most of her time outdoors, on her grandparents’ rooftop terrace, soaking up the sun on cool winter days and sleeping “under the stars” when it was too hot inside in the summer.
The book, and her experience reading it, were “transformational,” Tandon says. “I was sitting at a beach with my kids playing uninterrupted for a long stretch, and really recognizing that, wow, there’s something to this that has made parenting easier for me, while promoting our health and our well-being, for both of us.”
Preventive medicine drew Tandon to medical school, she says, and she chose pediatrics “because of this immense capacity to influence health early in life.” She was already studying and promoting physical activity for kids when she read Last Child in the Woods, so investigating the health benefits of time outdoors and in nature was a logical extension of her research.
“As a scientist myself, I was curious. Although this feels like the right thing, what is the evidence around it?” Tandon recalls thinking. She knows firsthand how little time clinicians have with each patient, how they must prioritize what topics to discuss and what advice to give in each encounter. “We want to focus on things that are evidence based and are going to influence health,” she says.
Tandon and some colleagues combed through the literature on nature contact and health. They found hundreds of studies, of adults and of children, but no systematic review of the research on kids’ health. So they wrote it. Their 2021 paper, published in Pediatrics, includes almost 300 articles and categorizes different types of exposure to nature and their health outcomes. The findings were overwhelmingly positive.
“The list of benefits of outdoor time for children and adults is long, and it includes things like healthier vitamin D levels, healthier weight status, better concentration for those with ADHD, lower blood pressure, lower stress,” Tandon said in a 2023 TEDx Talk. Time in nature also correlates with less depression and anxiety; better pregnancy outcomes; even lower rates of nearsightedness.
“That systematic review definitely was the foundation of what I’ve been able to do since then,” Tandon says, including her recent book, Digging Into Nature: Outdoor Adventures for Happier and Healthier Kids, coauthored with Danette Swanson Glassy, MD, and published by the American Academy of Pediatrics.
Yet Tandon is wary of a blanket prescription for nature. People are busy; some don’t have safe spaces outside near their homes. “Equity in access to green spaces and nature is an important part of promoting health equity,” she says. Plus there are health risks outdoors: air pollution, wildfire smoke, allergens like pollen, extreme heat and cold, insect bites and stings, and poisonous plants, to name a few. Some people have physical limitations that may restrict their 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, awareness of the connection is not new. Hippocrates suggested that fresh air and natural environments are good for us; Ayurvedic practitioners, Celts and Druids, Taoists, Buddhists, and monks of the Middle Ages all touted trees, plants, gardens, and forests for their healing properties.
There’s a certain obvious logic to this connection: “The outdoor world, historically, as human beings—that’s our natural environment,” says Mariah Stump RES’15, MD, MPH, 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 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 noticeable 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 researchers of forest bathing—the centuries-old practice of immersing oneself in the woods to improve wellbeing—have recorded significantly higher natural killer cell counts among practitioners, which lasted for days or weeks afterwards. The effect 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.
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 about seven hours a day staring at screens. “We just aren’t built for this,” she says.
Last fall, Brown hosted Nature and Health, a three-day workshop that invited researchers from across the US and the globe to explore the natural world’s effects on our health and well-being, from the cellular to the societal levels. Moore, who was a member of the steering committee, says Brown’s intrinsic multidisciplinarity made it “a fabulous place” for the engineers, social scientists, primary care physicians, computer scientists, psychiatrists, neuroscientists, and other experts to gather and share ideas.
“One of the fantastic things this meeting surfaced is that the problem of nature and health is one you simply cannot address at a single level,” he adds. “Brown’s good at thinking about systems in complex ways.”
A neuroscientist, Moore studies rodents to understand how the systems of the body, both neural and non-neural, work together to perceive the world. At the conference, he talked about how 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.
Workshop participants also discussed alternatives to being in nature, from looking out a window to VR experiences. Kelly Holder, PhD, another steering committee member, says these inspire her, in her role as chief well-being officer for the Division of Biology and Medicine, to bring nature into the Medical School in the form of photos and live plants.
“While we do have the natural benefits from the physical properties of plants and the fresh air, we also get something from looking at nature,” Holder says. She’s also shared with students an app that was presented at the workshop called NatureDose, which measures an individual’s time in nature. “When we observe a behavior, it aids us in changing that behavior,” she says.