Melissa Lem is a Toronto family physician who works and hikes in rural and remote communities across Canada. She holds a faculty appointment with the Department of Family and Community Medicine at the University of Toronto, guest blogs for Evergreen and regularly appears as a medical expert on CBC television's lifestyle show Steven and Chris. She had a recent conversation with the David Suzuki Foundation.

DSF: How stressed are most Canadians? How is their health affected?

Dr. Lem: A recent survey revealed that over 70 per cent of Canadian adults report excessive stress levels, with young adults bearing the brunt at 90 per cent. This translates into real impacts on the health care system and economy. In 2011, over $42 billion was spent on treatment and support services for mental health problems. Canadian employers lose an estimated $20 billion per year due to stress-related illnesses, which are the number one reason for sick leave.

Chronic distress releases a toxic brew of hormones and neurotransmitters into the body, keeping it in a state of high alert. Long-term exposure to cortisol, the primary stress hormone, can lead to impaired immune function, diabetes, heart disease, infertility and premature aging. Unmanaged stress makes your mind and body feel like they're running a marathon every day--without the health benefits.

DSF: What's the connection between stress and time in nature?

Dr. Lem: There are two popular explanations for how green time soothes a stressed brain. The first suggests that humans have a finite capacity for sustained concentration. Busy urban environments make focusing more difficult, causing fatigue and irritability. But nature lets the conscious brain rest, replenishing your powers of attention and lowering anxiety.

Another theory argues that affinity for nature was an evolutionary advantage. Landscapes with vegetation and water were ideal for finding food and avoiding predators, so their inhabitants survived longer and were less stressed. Although today's humans roam cityscapes with blinking stoplights and shiny glass towers, it's unlikely our brains have fully adapted to them.

Research indicates that spending time in nature supercharges the benefits of exercise, a proven stress reliever. I often recommend that my patients seek out green space to optimize their mental and physical wellness.

DSF: What are some interesting findings on the topic?

Dr. Lem: Some of the most compelling and biologically relevant evidence comes from Japan, where shinrin-yoku or "forest bathing" has long been recognized as an important part of a healthy lifestyle. A recent study showed that adults who spent three days in forests dramatically boosted their levels of cancer-fighting proteins and natural killer cells, reflecting lower stress. Another demonstrated that young men who spent just 15 minutes sitting in the woods instead of the city experienced significant drops in heart rate and salivary cortisol.

Within urban environments, office workers whose windows look out onto trees and flowers consistently report greater job satisfaction and personal welfare. Filling our cities with green space is a population-level intervention that makes all of us happier and healthier.

DSF: What can individuals and workplaces do?

Dr. Lem: A redesign of our mental and physical landscapes can make it much easier to connect to nature in the city.

Urban dwellers can mindfully search out micro-experiences in nature. Put away the smartphone and look for wildlife in city parks and gardens on your lunch hour. Bring nature home--create a native ecosystem in your living space so you can enjoy more green time and less screen time.

Workplaces can incorporate natural elements inside and advocate for community greening projects outside. Employers should encourage green break times and reimburse workers for health-promoting costs like passes to provincial parks and ecological urban attractions--investments in both collective well-being and the bottom line.

DSF: Do you have any tips for those who find getting out in nature daunting?

Dr. Lem: The key to success is making consistent and sustainable lifestyle changes. Start small, write down and be detailed about your goals. Schedule a weekend walk through a park with friends instead of sipping your lattes in a caf, or plan 30 minutes in a neighbourhood garden on your way home from work. Volunteering for local urban greening organizations is a great way to immerse yourself in nature and give back at the same time.

Don't be afraid to engage the support of your family, friends and larger network and put peer pressure to use. Get your daily dose of green time and spread good health from your cerebral cortex to your community and beyond.