Does nature soothe the brain and heal the body?

For the most part, our brains have not evolved in urban environments. Yet within a few decades, almost 70 per cent of the world’s population will live in cities. Despite the prosperity we associate with cities, urbanisation is a major health issue. The fast pace of urban life is a source of stress. We see the consequences on the brains and behaviour of people who have grown up in a city or live in one.

On the positive side, city dwellers are on average wealthier and enjoy better health care, nutrition and sanitation. On the other hand, they are more vulnerable to chronic diseases and face a more stressful and demanding social environment and greater inequalities. In fact, urban residents are 21 per cent more likely to suffer from anxiety disorders. In the case of mood disorders, this risk rises to 39 per cent.

A study published in Nature links living in an urban environment to sensitivity to social stress. MRI scans reveal that greater exposure to urban environments can lead to increased activity in the cerebellar amygdala, a part of the brain linked to emotions such as fear and the production of stress-related hormones. According to the study, the cerebellar amygdala “plays an important role in anxiety disorders, depression and other behaviours more prevalent in cities, including violence.”

The researchers also found that people who lived in urban areas for the first 15 years of their lives had increased activity in the area of the brain that helps regulate the cerebellar amygdala. Therefore, if you grew up in a city, you may be more vulnerable to stress than people who moved there later.

Author and professor David Gessner says that we turn into ‘high-strung’ animals. It’s as if an alarm clock goes off in our brains every 30 seconds, undermining our ability to concentrate for long periods. With urban life comes a constant need to filter information, avoid distractions and make decisions. We give our brains little time to recover.

How can we slow down the pace? It seems that the solution lies in nature. Cognitive psychologist David Strayer hypothesises that “being in nature allows our prefrontal cortex, the control centre of our brain, to slow down and rest, like an overworked muscle”.

Studies have shown that even brief interactions with nature can soothe the brain. Gregory Bratman of Stanford University conducted an experiment in which participants took a 50-minute walk in a natural or urban environment. People who took a walk in nature experienced a decrease in anxiety, rumination and negative emotions, as well as an increase in their memory capacity. Indeed, Bratman’s team found that walking in nature contributed to a decrease in rumination, the unhealthy but common habit of rehashing the causes and consequences of negative experiences. Their study also showed that nerve activity in the area of the brain associated with risk of mental illness decreased in participants who walked in nature, as opposed to those who walked in urban areas.

Korean researchers studied the differences in brain activity of volunteers who looked only at urban landscapes and those who looked only at natural landscapes. MRI scans of those who were presented with urban images showed an increase in blood flow to the cerebellar amygdala area. In contrast, those who were exposed to natural scenes showed increased activity in brain areas associated with empathy and altruism.

Researchers in Japan have found that people who engage in shinrin-yoku, or ‘forest bathing’, inhale ‘beneficial bacteria, essential oils from plants and negatively charged ions’, which interact with gut bacteria to boost the body’s immune system and improve mental and physical health.

Spending regular time in nature is not a panacea for mental health, but it is an essential part of psychological health and resilience. Nature helps us to cope with life’s difficulties and to recover. Even city dwellers can easily soak up nature – in a local garden, park or trail – to give their overworked brains a break.