Forests are an amazing resource. They give us everything we rely on in order to exist. They produce oxygen, cleanse the air we breathe and purify our water. They stop flooding rivers and streams and the erosion of mountains and hills. They provide us with food, clothing, and shelter, and with the materials we need for furniture and tools. In addition to this, forests have always helped us to heal our wounds and to cure our diseases. And, from time immemorial, they have relieved us of our worries, eased our troubled minds, restored and refreshed us. Until recently, however, there was little scientific evidence to support what we always known innately about the healing power of the forest.

In Japan, we practice something called forest bathing, or shinrin-yoku. Shinrin in Japanese means ‘forest’, and yoku means ‘bath’. So shinrin-yoku means bathing in the forest atmosphere, or taking in the forest through our senses.

This is not exercise, or hiking, or jogging. It is simply being in nature, connecting with it through our sense of sight, hearing, taste, smell and touch. Indoors, we tend to use only two senses, our eyes and our ears. Outside is where we can smell the flowers, taste the fresh air, look at the changing colours of the trees, hear the birds singing and feel the breeze on our skin. And when we open up our senses, we begin to connect to the natural world.

When people started to practice shinrin-yoku, in the early 1980s, it was based only on common sense and the intuitive idea that being in the beautiful green forests of Japan would be good for us. The term was invented in 1982 by the then Director General of the Agency of Agriculture, Forestry and Fisheries of Japan, Tomohide Akiyama, who stated that the people of Japan were in need of healing through nature. The idea was also part of a campaign to protect the forests. If people were encouraged to visit forests for their health, they would be more likely to want to protect and look after them.

It was not until 2004 that scientific investigation of the link between forests and human health began in earnest. Together with various government agencies and academic organizations in Japan, I helped found the Forest Therapy Study Group, with the express aim of discovering what it is about trees that makes us feel so much better. The following year, I set off for Iiyama city, in the mountainous northwestern corner of Nagano Prefecture, taking twelve healthy middle-aged businessmen from Tokyo with me for a three-day scientific forest-bathing trip.

The forests of Iiyama are some of the most beautiful and unspoilt in Japan. With the giant beech trees of Mount Nahekura and the snowmelt waters of the Chikumagawa (also known as the Shinanogawa), the country’s longest river, the landscape is romantic and quintessentially Japanese.

It was in Iiyama that we first scientifically proved that forest-bathing can:

  • Boost the immune system
  • Increase energy
  • Decrease anxiety, depression and anger
  • Reduce stress and bring about a state of relaxation

Based on the results of that forest-bathing study in April 2006, Iiyama became the first location in Japan to receive forest-therapy certification. The ‘green healing’ power of Iiyama’s forests had been scientifically demonstrated. There are now sixty-two certified forest-therapy bases in Japan, all of which have been proved to have particular healthful properties, and between 2.5 and 5 million people now walk the forest trails every year.

We have now conducted numerous studies and collected a huge mass of data from hundreds of people on the impact of forest-bathing on various aspects of human health. For example, we discovered that forest-bathing can help you sleep – something I studied in Iiyama city with those twelve businessmen.

The participants took two-hour walks in the morning and afternoon in different forests. They walked around 2.5km in two hours – roughly the same distance they would walk on a normal working day. I measured their sleep activity with a sleep polygraph and an accelerometer – a counter you wear on your wrist like a watch which judges the number of physical movements you make – before, during and after the trip. Fewer than forty body movements in a minute indicates that a person is asleep.

Before the forest-bathing trip, these men had an average sleep time of 383 minutes. On the nights during the trip, this rose to 452 minutes. And on the night after the trip, it was 410 minutes. In other words, there was a significant increase in sleep time during the forest-bathing trip, proving that you sleep better when you spend time in a forest, even when you don’t significantly increase the amount of physical activity you do.

Another sleep study reported by other researchers looked at how forest-bathing improved sleep for a group of people who suffered from sleep complaints of one kind or another, from insomnia and difficulty falling asleep or staying asleep to waking up early in the morning. The group walked for two hours in Ryukoku forest in the western part of Honshu. Sleep was measured the night before and the night after. Comparisons were made between the two nights and between people who walked in the morning and in the afternoon.

Here are some of the findings:

  • The average sleep time of participants after a two-hour forest walk increased by 15 percent, or fifty-four minutes
  • Participants were significantly less anxious after a two-hour walk in the forest
  • Quality of sleep was better after forest- bathing
  • Afternoon walks improved the quality of sleep more than morning walks

The good news is that even a small amount of time in nature can have an impact on our health. A two-hour forest bath will help you to unplug from technology and slow down. It will bring you into the present moment and de-stress and relax you. When you connect to nature through all five of your senses, you begin to draw on the vast array of benefits the natural world provides. There is now a wealth of data that proves that shinrin-yoku can:

  • Reduce blood pressure
  • Lower stress
  • Improve cardiovascular and metabolic health
  • Lower blood-sugar levels
  • Improve concentration and memory
  • Lift depression
  • Improve pain thresholds
  • Improve energy
  • Boost the immune system with an increase in the count of the body’s natural killer (NK) cells (see p. 83)
  • Increase anti-cancer protein production
  • Help you to lose weight

I can’t think of a better way to establish our connection to the forest, to feel its power and importance for ourselves, than to go for a forest bath. When you are intimately connected to the forest through all five of your senses, you feel restored and refreshed. The forest can bring you back to health and life, and you will want to conserve and protect it in turn.

From FOREST BATHING: How Trees Can Help You Find Health and Happiness by Dr. Qing Li, published on April 17, 2018 by Viking, an imprint of Penguin Publishing Group, a division of Penguin Random House LLC. Copyright © Qing Li, 2018.