In evolutionary terms, humans have always lived outdoors in nature. That is why our biological "normal state" is to be surrounded by natural stimuli. Our body is therefore best attuned to life in a natural environment.
It was only with the onset of urbanisation that we began to live in a greatly altered and partly artificial environment, and this could be partly responsible for a large number of chronic functional disorders and feelings of stress in modern man.
Shinrin-yoku is a simple way to escape the stress of the city and everyday life. Loosely translated from Japanese, it means "absorbing the forest atmosphere with all your senses" or forest bathing for short. This is categorised as a natural or eco-therapy and is also becoming increasingly popular in our western world. Science is also looking closely at the physiological effects of being surrounded by nature. Forest bathing can strengthen the immune system against viral or bacterial infections, prevent cancer, relieve stress and promote relaxation. Our organism has been accustomed to the bacteria, viruses, fungi and plant substances found there for millions of years. They are therefore old friends to us and promote our immune tolerance.
What makes the forest air so special?
The forest air is a highly potent cocktail of bioactive healing substances, the phytoncides, a collective term for a group of antibiotically active substances from plants.
Terpenes are a significant group of these healing substances in the forest air. They are found in essential oils, for example. Over 40,000 of these secondary plant substances can be distinguished. They have a variety of different functions. For example, they serve as protection for the trees in strong sunlight, visible as a blue haze over the forest. They also act as a plant attractant for insects and animals. They are also used by plants to warn other plants of pests. Plants can then produce terpenes as a poison to kill pests or repel them with an unpleasant flavour. They also help trees, fungi and herbs to communicate.
Terpenes have a strengthening effect on the immune system and are anti-carcinogenic. Terpenes strengthen the immune system directly via the effect of the hormone system by reducing stress hormones. The most terpenes are found in the forest in summer, the least in winter. Terpenes are particularly intense in the forest during rain or fog. We find them in the highest concentrations near the ground, i.e. where we usually spend most of our time. Conifers in particular release terpenes. Also deciduous trees, especially beech, oak, birch and hazel.
Influence on the immune system
A walk in the forest has been proven to strengthen the immune system
A single day in the forest increases natural killer cells by almost 40 per cent, and by more than 50 per cent on the second day. These cells are also fitter. The increase in the activity of these cells after one day in the forest is even detectable for the next seven days. If you stay in the forest for three days, the number of killer cells increases for the following 30 days.
The forest air also has a positive effect on oxidative stress in our bodies. This is triggered by free radicals, which are particularly reactive. In one study, lipid peroxidation was reduced in test subjects who spent time in the forest. Lipid peroxidation is the chemical process in which these free radicals begin to oxidise the body's own fats and thus destroy them. Forest bathing can therefore prevent the development of a chain reaction that can lead to damage to the cell membranes. A reduction in inflammatory cytokines was also observed in this study.
Improvement of pain
In addition to the metabolic changes caused by forest bathing, the sounds and images of nature alone can influence the perception of pain. For example, a study in the USA found that simply listening to nature sounds and being shown a nature scene was able to alleviate pain during a bone biopsy in contrast to city noises and no sounds.
Metabolic adjustments such as a reduction in blood sugar and triglycerides
Shrinin-joku (Japanese term for forest bathing) can also have a positive effect on the metabolism. Studies have shown that a walk in the forest can reduce triglycerides. Triglycerides are fats that are stored in fatty tissue as an energy reserve. Some people have elevated triglyceride levels, e.g. if they have a lipometabolic disorder. In this case, forest bathing can be a supportive means of normalising the metabolism. Another effect of forest bathing on the metabolism is an increase in the tissue hormone adiponectin, which has a positive influence on fat and sugar metabolism. Low adiponectin levels are also linked to diseases such as type 2 diabetes and coronary heart disease, as it influences insulin secretion. The body also produces more anti-carcinogenic proteins.
Relaxation and stress reduction through forest bathing
A stay in the forest also acts as a highly potent psychotropic drug with no side effects, relaxing and relieving stress. The forest has a stress-relieving effect on our autonomic nervous system - via psychological influences as well as terpenes. For example, it has been proven that stress hormones such as cortisol and adrenaline are sustainably reduced.
In men, adrenaline levels drop by almost 30 per cent after a day in the forest compared to the initial value and by 35 per cent on the following day. In women, the values even fell by 50 per cent on the first day and by 75 per cent on the second day. Researchers were also able to prove that a stay in the forest led to a reduction in feelings of anxiety, aggression and exhaustion.
Deep, dark forests are not as relaxing as a savannah-like, light-coloured environment with tall trees and clearings that we can overlook. The latter supports our need for protection and safety and promotes our relaxation. But it is not only forests that relax us, many natural elements calm us: flowers and shrubs (also in the home), flowering areas, meadows and clearings with scattered trees, gardens with fruit trees and vegetable patches, soil overgrown with mushrooms, birds as well as calm flowing or standing water and the sea.
The scientist Qing Li, author of the book 'Forest Medicine' published in 2012, advises spending two to three days a month and around four hours a day in the forest to achieve a lasting increase in anti-cancer effects and natural killer cells.
But you don't have to do that much. Just try to organise a long walk in the woods once a week and spend time in the countryside whenever possible, for example during breaks or when doing sport. If you are lucky enough to have a garden or a park in your neighbourhood, use it as often as possible.
Effects on the mood
A review from 2019 looked in detail at the psychological effects of forest bathing. Various emotional states were categorised. These included depressive mood, tension, anxiety, fatigue and anger. Without exception, an improvement was observed in each category after bathing in the forest. This can therefore help to release negative emotions in order to create space for positive feelings!
Better concentration
Green surroundings benefit physical and mental health and improve attention. New studies on young adults have shown, for example, that short periods spent in nature improve memory and attention. Even just looking at pictures of nature helps. Similar results have also been obtained in studies with older people. Listening to the sounds of nature also seems to improve attention. Back in the 1990s, Stephen Kaplan founded the "attention restoration theory", which states that a natural environment is less cognitively stressful than an urban environment and therefore concentration can be better maintained. Therefore, whenever possible, move your work to the countryside - or at least your work breaks - and use green images of nature for your next wallpapering.
Beneficial effects on children
Spending time in nature also promotes concentration and attention in children, e.g. those with attention deficit disorder (ADD).
Children in a forest kindergarten are sick less often, are less overweight, and their concentration and gross motor skills are better developed.
Green prolongs life and improves birth weight
The results of a 2015 review by James and colleagues are truly impressive. His research findings suggest that green protects against negative
The green environment has a positive effect on mental health, cardiovascular disease and mortality. A green environment also has a positive effect on birth weight during pregnancy.
Green lets you move and normalises body weight
In fact, the more you spend time outdoors, the more you move and the more ideal your body weight is.
Another study from 2017 comes to a similar conclusion: increased green spaces in residential areas are associated with a lower risk of suffering from several frequent causes of death.
Reduction in mortality from air pollution
The mortality rates from air pollution, such as fine dust pollution, are also reduced with more green surroundings. I really wish that urban developers would read these studies and that grey high-rise landscapes would soon be a thing of the past.
Heart health
Blood pressure also falls when people are in a forest environment, according to a systematic review by Ideno and colleagues from 2017, in which over 20 studies with 732 test subjects were analysed. Not only does the systolic value fall, but also the diastolic value, which is otherwise much more difficult to influence. This was also confirmed in other studies.
In addition to the positive influence of forest bathing on blood pressure, it also helps patients with chronic heart failure. A study showed that a four-day stay in the forest significantly improved the parameters associated with this condition. Forest bathing can therefore favour the functional condition of our heart.
Sleep
And, the more contact you have with nature, the better you can sleep, and this also works for older people. So throw your sleeping pills in the bin and enjoy a few romantic nights in nature.
So, are there any reasons not to spend some time in the countryside today?
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