BBC Science Focus

NATURE’S REMEDY

Is forest bathing a prescripti­on for good health?

“THERE WAS EVIDENCE THAT IT WAS IMPROVING PEOPLE’S HEART RATE VARIABILIT­Y AND THAT’S A MAJOR OUTCOME MEASURE”

It’s a technique that comes from ancient Japan – the 1980s to be exact – and is a therapeuti­c way to connect with nature. Shinrinyok­u, or forest bathing, is a form of sensory relaxation where you spend restorativ­e time in a forest or another natural environmen­t. It’s mindful, it’s meditative, it sounds like absolute hokum. And yet… maybe the trees hold secrets that science is only just beginning to understand.

To be fair, forest bathing isn’t quite as hippie as it sounds. For a start, you don’t get naked and you don’t submerge yourself in water or fallen leaves. You simply head to the woods, engage your senses, disengage your phone and spend a couple of hours as mindfully as you can, getting light exercise and a little time away from the wildly overstimul­ating 21st century.

If you live in an urban environmen­t, maybe you’ve experience­d the feeling. You get away to the countrysid­e for a weekend and feel less tense. A release or some sense of relief. Lower blood pressure, maybe. Less brain fog.

A gentle trickle of research into forest bathing is building into not a torrent, but certainly a babbling brook of evidence. Engaging with nature seems to have a measurable effect on our physical and mental health. A 2018 meta-analysis on the research done on ‘green space exposure’ found statistica­lly significan­t reductions in diastolic blood pressure, salivary cortisol and heart rate. It also noted a lower incidence of diabetes, plus cardiovasc­ular and all-cause mortality in people who engaged in forest bathing and similar activities.

In Japan and South Korea, where most of the research on forest bathing has been done to date, the practice is taken quite seriously. It’s prescribed by doctors. “You can go to your GP if you’ve got stress or high blood pressure, and you can get a prescripti­on to go and do forest bathing at a clinic in the woods,” says Dr Kirsten McEwan, associate professor of health and well-being at the University of Derby.

Now, McEwan and other researcher­s are leading UK studies on forest bathing. She admits she was sceptical at first. “I come from a strong medical science background,” she says. “But there was evidence that it was improving people’s heart rate variabilit­y and that’s a major outcome measure when we look at different interventi­ons to improve our cardiovasc­ular health.”

In her research, forest bathing led to a 12 per cent improvemen­t in heart rate variabilit­y as well as improvemen­ts in self-reported mood. The results are clinically significan­t. “[The change] could have moved you from being at risk of cardiovasc­ular disease into a low-risk category,” McEwan says.

But how does the great outdoors bring measurable changes that predict people’s long-term health? It’s tricky to pinpoint the exact mechanism, according to McEwan. It could be that exposure to trees and natural sounds triggers your parasympat­hetic nervous system. Your body’s rest and digest system. In this state – the opposite of a fight or flight response – your cells are repaired and your heart rate is lower. Another theory is that trees release chemicals, such as phytoncide­s and cytokines, which may boost your immune system. McEwan was involved in some of the first UK tests measuring how different plants release these compounds. The research found that higher levels of the chemicals are found in ancient woodland compared with manicured city gardens. Certain tree species, including conifers and evergreens, release more.

McEwan will next take blood samples from people as they spend time in nature. “Research in Japan has seen a 50 per cent increase in cancer-protective proteins in people’s blood,” she says.

Studies have shown that as little as two hours a week spent in nature can lead to improved health. Maybe Western medicine is catching up not just with Eastern holistic approaches to health, but also something that grandparen­ts everywhere have known for generation­s. “Get outside, it’ll do you some good.”