There's a painting in the Art Gallery of NSW that sums up summer in Sydney for me. It's Albert Hanson's Pacific Beaches (1898): a deserted Sydney beach in the late afternoon, westerly sun beating down on the sandstone sandstone cliff. It's scorching hot, with a breeze barely ruffling the water, but we're in the shade looking out from a cool spot under the trees. I look at the picture and feel my breathing slow and my shoulders relax. Is it just because it feels so good to be at the beach in the shade when the sun is hot enough to prick your skin?
Certainly shade is one of the great benefits of trees to human health. Researchers estimate that trees lower the surrounding temperature by at least six and up to 20 degrees. And it's not the only health benefit. Trees also boost immune function and decrease blood pressure thanks to the beneficial bacteria and phytochemicals that are either released by trees or live in their embrace.
Much of the early research pinning down reasons for tree-related wellbeing was conducted in Japan, where "forest bathing", shinrin-yoku, is now something a professional health might advise you to add to your health. Forest bathing is a walk through trees (we could call it a bush walk) with the Fitbit turned off and focus switched from self to world. As you might expect from a country that officially ranks its gardens and its sunset-viewing spots, there are designated "forest-bathing" hotspots throughout Japan.
It turns out you do not even have to walk through trees to share their stress-busting benefits. Looking is enough, even at a picture. The theory that explains how this can possibly work is called "fractal fluency". Fractals are patterns that repeat across scales – like a tree branching from the trunk, and continuing to branch, right down to the twigs and leaf structure. Researchers came up with the theory by trying to understand why the viewers had a positive physiological response when looking at a painting by Jackson Pollock, but not when they looked at a fake Pollock. Pollock's painting are fractal, the fakes were not.
Fractals are everywhere in nature and our visual system has evolved to process fractals with ease. As a result, looking at fractals makes us feel good, to the tune of a 60 percent reduction in biological measures of stress. After I read this research I had another look at Hanson's Pacific Beaches; sure enough the trees that screen the view are fractal.
The research suggests you need a couple of minutes looking at trees, or at pictures of trees, to start to get stress-relieving benefits. So by all means, slow down and smell the roses, but do not forget to look at the trees, or even better, to bathe in them.