“There’s an urgent need emerging in science and at the gut level to increase the nature experience. This field is just exploding,” says Gretchen Daily, a professor of environmental science at Stanford University.

The benefits have been clear to scientists for some time, but the pandemic has made the matter more urgent. The physical and emotional toll the virus has taken, especially in urban areas with little green space, has galvanized doctors, researchers and others to tap into nature’s therapeutic effects.

Spending time in the woods—a practice the Japanese call “forest bathing”—is strongly linked to lower blood pressure, heart rate and stress hormones and decreased anxiety, depression and fatigue.

Scientists have repeatedly found that human anticancer natural killer cells significantly increase after walks in a forest. In one such study, published in 2010 in the Journal of Biological Regulators and Homeostatic Agents, the number and activity of killer cells increased in a group of twelve healthy men after two walks, each two hours long, in a one-day trip to a forest park in the Tokyo suburbs. So did anti-cancer proteins, according to the research led by Qing Li, an associate professor at the Nippon Medical School. Cortisol in the blood and adrenaline in the urine significantly decreased. The effects lasted at least seven days, the researchers found.

Time in a forest is linkednefi to decreased inflammation, which has been implicated in chronic disease.

“People are deciding whether or not this type of coffee bean or that type is better for you, when there is such an obvious health tool at your disposal. You literally just walk outside. People don’t know,” says Jared Hanley, co-founder and CEO of NatureQuant, a startup working on an app for users to track the time they spend in nature much like they count steps.