You'd be hard-pressed, these days, to find a psychologist who doesn't think we'd be better off if we spent more time in nature. The problem, for those of us who live in cities and work at desks, is the "time" part: there never seems to be any. Whenever I make it into the hills for a couple of days, I'm so rejuvenated I swear I'll start doing it fortnightly. Then I don't. "Climb the mountains and hear their good tidings… the winds will blow their own freshness into you, and the storms their energy," wrote the naturalist John Muir, enticingly – but that's too rarely an option. Very well, say the wilderness evangelists: at least spend an hour a day in your local park. Because who doesn't have a spare hour a day – apart from, well, lots of people? The research testifying to the benefits of immersion in nature keeps piling up. But it's not much use if you never get around to the immersing.
It's cheering, then, that a clutch of recent findings have begun to demonstrate how even the tiniest kinds of engagement with nature deliver a psychological boost. When you can't climb mountains, it turns out, merely blurring the boundary between indoors and out may suffice. Office workers who glimpse a tree or two are both happier and more productive; in one analysis, of a university building in Oregon, workers on the greenery-facing side took 19% fewer sick days. If you're treated in hospital for bipolar disorder, the evidence suggests, you'll be discharged several days sooner on average if your room is naturally lit. Pupils do worse in tests in windowless classrooms. Even looking at photographs of natural scenes lowers blood pressure. Taking things to a seemingly absurd extreme, German researchers reported last year that merely seeing a green rectangle for two seconds led to measurable improvements on creative tasks, compared with rectangles of white, grey, blue or red.
What's going on? The green-rectangle researchers thought it might be some subconscious association with the idea of growth, and therefore creativity. But the dominant explanation remains that of "biophilia", coined by EO Wilson, which he described as our "urge to affiliate with other forms of life" – probably because we evolved to function best in nature-rich settings. As Lance Hosey points out in The Shape Of Green, there's even one version of this idea, called the Prospect/Refuge Theory, according to which we're happiest looking out at nature from places of safety, with a good view of predators and no need to watch our backs. Perhaps seeing the woods from your kitchen window can be more enjoyable than tramping through them.
You could interpret all this as an argument for inactivity – why leave the house? – or, worse, as nothing but a way to squeeze more labour out of people. (Call-centre employees work 6-12% harder with a good view of greenery, one study claims.) I'd prefer to see it as an argument for making a conscious effort to lower the barricades between indoors and out, at home and at work – by means of pot plants, windows that actually open and office buildings that don't take 15 minutes to leave or re-enter. The architect Steve Mouzon calls this "living in season", instead of trying to maintain one climate-controlled year-round indoor season. In the meantime, I've changed the image on my computer's desktop wallpaper to green leaves. It's a start.