Since 2004, studies conducted in Japan on this recognized mode of relaxation and stress management have been very clear in their conclusions. (1) : contact with the wild nature allows in particular a reduction of blood pressure, heart rate, stress, anxiety, depression and fatigue.
Part of these benefits are linked to an air loaded with aromatic molecules (those found in essential oils) and negative ions, these air particles enriched with electrons that are found in greater quantities in nature. During forest baths, there is a reduction in the activity of the sympathetic nervous system (which activates the nerves), an increase in the activity of the parasympathetic nervous system (which calms the nerves), a decrease in the production of stress hormones (adrenaline, noradrenaline, cortisol) as well as increased activity of certain lymphocytes (NK: Natural Killer) which improves the effectiveness of the immune system. A priori, no type of forest seems more beneficial than another.
Islands of green in the city, multipurpose drugs
But the benefits of trees are not limited to moments of walks and exercises in the forest, and can be felt every day in our places of life and activity. In 2022, Cecil Konijnendijk issues his “3-30-300” theory to take advantage of the benefits of trees (2) : be able to see at least 3 trees from home, work or school; benefit from at least 30% of wooded area in its immediate environment, and not live more than 300 m from an accessible green space. In a study to test this theory (3)a team of researchers confirmed the benefits of this rule of life on the mental health of Barcelonans, while noting that barely 5% of them strictly fulfilled the conditions of the “3-30-300”.
A Finnish team, in 2022 (4)highlighted that the regular frequentation of green and blue spaces (lakes, seashores, etc.), by urban residents, several times a week, made it possible to reduce the use of psychotropic (-33%), antihypertensive (-36%) and anti-asthmatic drugs (-26%). On the other hand, being content to have these spaces nearby, or to observe them from one’s window, did not translate into a reduction in the use of drugs.
Sylvotherapy appears particularly indicated for urban residents who have a higher risk hypertension and psychological stress than rural residents. In a December 2022 meta-analysis (5)including 21 studies on blood pressure (2,270 participants), and 13 studies on salivary cortisol used as a marker of stress (1786 participants), evidence considered “strong” showed that sylvotherapy has beneficial therapeutic effects on the physiological and psychological health of urban residents by reducing blood pressure and stress (through lowering cortisol). THE sessions lasting 20 minutes or more were more effective than those lasting less than 20 minutes.
But what if you don’t have daily access to green spaces, or the forest is too far away? A Japanese study from 2022 (6) sought to assess the physiological and psychological therapeutic effects of a “digital forest bath” set up in an urban installation, and reproducing the visual, auditory and olfactory elements of a “real” forest bath. Just like an immersion in the forest, digital reproduction has generated a significant increase in activity of the parasympathetic nervous system and a significant reduction in heart rate. Participants noted an improvement in their mood, including reduction of tension, anxiety, depression, anger, hostility, fatigue and mental confusionbelieving that this digital environment has allowed a “restoration” of their psychological state.
Digital forest bathing obviously does not replace contact with “real” nature, but in any case allows you to enjoy some of its benefits.
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