City life undoubtedly brings multiple advantages, such as greater access to services, job opportunities and social life. As a result, more than half of today's population lives in cities and this is expected to increase to 68% by 2050.

At the same time, nature tourism is also becoming increasingly popular. We live in cities but in our free time we seek to get out into nature to recharge our batteries. We need a break from asphalt and buildings because actually living in the city is a risk factor for mental health. Anxiety, depression, mood disorders and schizophrenia are up to 56% more common in the city than in rural areas.

By contrast, as soon as we enter a forest or other natural space our blood pressure drops, our heart rate decreases and our mood immediately improves. Why does this happen?

Plans in nature are often associated with physical exercise, the health benefits of which are well known, but a large body of research has shown that simply being in nature also brings significant physical and mental benefits.

One of the pioneering studies on this subject was carried out between 1972 and 1981 in a hospital in Pennsylvania. It was observed that, after surgery, patients recovered more quickly if the window of the room looked out onto a natural environment than if it looked out onto a building. Not only did these patients need less time in hospital, but they also required less painkillers and nurses noticed that they were in a better mood.

Since then, several scientific studies have shown that forays into nature make us happier because they reduce stress hormone levels and negative emotions, combat depression and facilitate quality sleep among many other benefits.

In addition, there are numerous improvements in cognitive performance. These plans have been found to help with work capacity, memory, attention, orientation and also promote children's imagination and creativity, as well as improvements in their school performance.

Inevitably, the brain is affected by the environment. In 2015, Stanford scientist Gregory Bratman conducted research showing that experiences in nature reduce the activation of the subgenual prefrontal cortex. This is an area of the brain associated with mental illnesses such as depression and anxiety. Reduced activation in this area is experienced as a reduction in repetitive thoughts focused on negative emotions.

In addition, a study on this topic was published in Nature last year 2022 and received considerable media coverage. Using a non-invasive technique called functional magnetic resonance imaging, the brains of 63 healthy volunteers were examined before and after they took a one-hour walk in a forest or on the streets of Berlin.

The biggest change in the volunteers' brains was detected in the amygdala, an area of the brain that plays an important role in stress and the processing of negative emotions. Its activation is necessary because it helps us survive in dangerous situations. Stress and fear are necessary emotions, but when they get out of control they can cause serious health problems.

The results of the study showed that amygdala activity was significantly reduced after the forest walk. Interestingly, the volunteers who walked in the city did not increase their amygdala activity, which contradicts the common belief that walking in the city is stressful.

Given this evidence, the next question is clear: Why does nature affect our brains in this way?

One hypothesis is that humans have an innate tendency to connect with nature that is rooted in our evolutionary history. We cannot forget that we are primates and for most of our evolution we have lived in nature. An environment with trees and water was advantageous for survival because the resources we needed were found here. Therefore, it makes sense that our body reacts positively to these stimuli.