I spend on average 90% of my time indoors. Screens, open spaces, transport, apartments, my brain evolves in artificial environments for which it was not designed. Yet after millions of years of evolving in natural environments, my nervous system still responds profoundly to contact with nature. Research into the psychological and physiological effects of exposure to nature has grown considerably over the past twenty years. A study published in PNAS (2015) by Bratman et al. shows that a 90-minute walk in nature reduces activity in the subgenual prefrontal cortex, the area of the brain linked to chronic ruminations, significantly more than a walk in an urban environment. Here's why and how to integrate nature into my life to make it a tool for mental health.
1. Why nature soothes my brain: the mechanisms
The restorative effect of nature comes through several documented neurobiological and psychological mechanisms:
Attention Restoration Theory (Kaplan, 1995): Natural environments solicit what Kaplan calls “involuntary attention,” a form of gentle, effortless attention that allows directed (voluntary, expendable) attention to regenerate. After an intense work session, walking in a park measurably restores the ability to concentrate.
Stress reduction theory (Ulrich, 1983): exposure to natural landscapes triggers a physiological response of rapid recovery from stress, reduction in heart rate, blood pressure and cortisol. This response is almost automatic and does not require conscious effort.
Phytoncides: trees emit volatile organic compounds (phytoncides) which, when inhaled, increase the activity of NK (Natural Killer) cells of the immune system and reduce cortisol. This is the scientific basis of Japanese “forest bathing” (Shinrin-yoku).
The connection to living things (biophilia): the concept of biophilia (Wilson, 1984) postulates an innate affinity of humans for living things and natural forms. This connection activates reward and safety circuits that reduce the alert state of the nervous system.
| Health indicator | Effect of exposure to nature | Source |
|---|---|---|
| Cortisol (stress) | 21% reduction after 20 min in a natural space (vs urban) | Hunter et al., Frontiers in Psychology, 2019 |
| Mental ruminations | Reduction in subgenual prefrontal cortex activity after 90 min of nature walking | Bratman et al., PNAS, 2015 |
| Blood pressure | Significant reduction after walking in the forest vs walking in the city | Li Q., Environmental Health and Preventive Medicine, 2010 |
| Immunity (NK cells) | 50% increase in NK activity after 3 days of forest bathing 13px;border:1px solid | Li Q., International Journal of Immunopathology and Pharmacology, 2009 |
| Mood and well-being | Significant improvement in mood, reduction in anxiety after 10 min in nature | McMahan & Estes, Journal of Positive Psychology, 2015 |
| Concentration | Improved attentional performance after a walk in nature vs urban | Berman et al., Psychological Science, 2008 |
2. What the science says: measurable effects
3. Shinrin-yoku: forest bathing as a therapeutic practice
Shinrin-yoku (literally “forest bathing”) is a Japanese practice developed in the 1980s and today recognized as a public health intervention in Japan. It's not hiking or strenuous exercise: it's a slow, mindful sensory immersion in the forest.
How to practice: I walk slowly (1 to 2 km in 2 hours), I stop often, I pay attention to all my senses, the sounds (birds, wind, crunching), the smells (earth, resin, moss), the textures (bark, leaves), the play of light. I let my mind wander without a performance goal or a specific destination.
Regularity takes precedence over intensity: studies show cumulative effects with practicing 2 hours per week in a natural space. Urban parks, peri-urban forests and gardens can be sufficient, no need for deep forests.## 4. Integrate nature into my professional and urban daily life
The green break. Replacing 10 to 15 minutes of my lunch break in an enclosed space with a walk in a park or garden reduces cortisol and restores focus for the afternoon. A simple habit with measurable impact.
The active journey in nature. Walking or cycling in green areas to work, even partially, combines the benefits of physical activity and exposure to nature, a double health dividend.
The weekend in nature. Two hours per week in a natural space (park, forest, seaside) are associated with significantly improved well-being according to White et al. (Scientific Reports, 2019). This is the documented minimum effective weekly dose.
Indoor plants. Even indoors, the presence of plants reduces perceived stress, improves air quality and creativity according to several studies in environmental psychology. An accessible and sustainable investment.
Structured ecotherapy. For people suffering from depression, anxiety or burn-out, ecotherapy programs (nature-based interventions, therapeutic gardening, therapeutic hiking) supervised by mental health professionals are developed in France and Europe.
5. Nature, prevention and health check-up
Exposure to nature is one of the most accessible, inexpensive and well-tolerated preventative health interventions available. It has no side effects, is compatible with all health profiles and can be integrated into a global prevention plan. In the context of a health check-up, evaluating my weekly exposure to nature and identifying levers to increase it is a simple and concrete prevention approach.
💡 tips to remember
- 20 minutes in a natural space reduces cortisol by 21%, effortlessly, without equipment, for free. It is one of the most effective and accessible anti-stress interventions available.
- The documented minimum effective weekly dose is 2 hours in nature. I can split it into several short outings, the effect is cumulative.
- I practice Shinrin-yoku during my next walk: I walk slowly, I stop often, and I pay all my attention to my 5 senses. It's not hiking, it's a sensory immersion.
- I replace part of my lunch break in an enclosed space with 10 to 15 minutes in a park or garden: this restores concentration for the afternoon in a measurable way.
- Even houseplants reduce perceived stress and improve creativity according to environmental psychology. A minimal investment for a real daily benefit.
