TORONTO -- A different sort of medical prescription is spreading across Canada, that of “nature therapy” where doctors, nurses and other health-care practitioners can prescribe going outdoors as part of a wellness routine.

Nature therapy, also called ecotherapy, is derived from the principles of ecopsychology – a broad term that describes using a person’s presence in nature to improve their mental and physical health.

“Green prescriptions” began as a grassroots movements in the U.S. more than a decade ago, and have spread globally since. But studies have shown that exposure to nature helps to lower anxiety, counters depression and improves blood pressure, immune function and sleep.

“I’ve really started appreciating the health benefits of nature time when I moved,” Dr. Melissa Lem, a family physician, told CTV News.

Lem noticed a change in her stress levels when she moved her practice from northern B.C. to Toronto, and felt like lack of access to nature was the source.

“I found that I felt a lot more stressed when I was in Toronto, and so one day I was sitting in my apartment…and looking out the window at the tiny little bit of sky I could see and thought…I think it’s because I’m missing nature time, that’s why I feel so stressed right now," she explained.

Lem says as she dove deeper into studying the health benefits of nature therapy, she discovered a new body of research which led her to create something she calls “Park Prescriptions.”

Park Prescriptions, an initiative of the BC Parks Foundation, is a program where health-care providers can write a prescription that advises patients to get out into nature, whether walking or biking, for at least two hours a week, and then track their progress at follow up appointments.

Lem plans on introducing an app to help make it easy for patients to track their time in nature and how their health has improved over time.

“Spending time in these busy urban environments tires our powers of conscious attention because we have to constantly focus on lights, crowds and traffic to navigate urban environments… spending time in nature is sort of this soft fascination that allows our brains to rest, it doesn’t require a lot of filter,” Lem explained.

“There are also theories around and some evidence behind phytoncides being released by trees and plants within natural settings that actually improve the function of natural killer cells and your immune system."

More than 500 health-care workers across Canada have signed up to participate in the Park Prescriptions program, including Hamilton, Ont., family doctor Meghan Davis.

Davis said that Park Prescriptions allows doctors to align their suggestions for nature therapy and reassure patients who might be struggling with anxiety or dealing with cancer that there is  "great science behind that suggestion.”

Those who work within the medical field also enjoy the idea.

Kelowna B.C. medical student Peter Singh says nature helped soothe him after his father’s illness in 2014 and eventual death.

“That was a very complicated time in my life…I was essentially just trying to get out of the house and run,” Singh told CTV News, adding that he was “lucky” there was a park nearby.  “The more I tried to run away from my problems… the more I found myself spending time in that green space and realized that I wasn’t just running away from my problems anymore I was actually running to this place.”

“I was seeking the comfort of the trees and the moss and the birds…you forget about things for just that 20 minutes, it was very valuable to me and mental wellbeing.”

Singh is now helping Lem bring her message and practice of Park Prescriptions to a wider audience through his membership of the Canadian Association of Physicians for the Environment so that more Canadians can access nature therapy in the future.