The value of nature for our mental health

Amidst the biodiversity crisis, we’re at risk of losing precious species and vital ecosystem services and resources. These issues are, rightly, top priorities - but did you know that nature has immense value for our mental health, too?

Our natural environment

Humans, like all animals, evolved amongst nature. Just a few million years ago, our hominin ancestors were living in the treetops and up until around 10,000 years ago - a blink in the evolutionary timeline - our ancestors slept in caves and spent their days hunting animal prey and gathering vegetables, nuts and berries. It is no wonder that we still feel a deep connection with nature - are genes evolved in the great outdoors.

Yet, in an increasingly urbanised world, fewer and fewer people have regular access to natural space. We are losing biodiversity at an unprecedented rate all over the world. And, at the same time, humans are suffering from rising levels of mental health issues and disorders. Exposure to green space has been shown to have beneficial effects on health and well-being, and this positive impact has far-reaching effects for public health.

The green experience

Nature can have a great variety of beneficial effects on mental health; it can improve mood, reduce negative emotions (like anger), reduce stress levels and encourage physical activity, which has its own incredible benefits for mental health and well-being.

There are two main theories about why nature has such beneficial effects - first, the idea that it restores our capacity to switch our attention from the problems of modern life to the simplicity of nature and, second, the idea that spending time in nature alters our emotions and reduces stress due to an innate connection with the natural world. These benefits might be even greater for children, whose opportunities relating to discovery, creativity, control and risk-taking are greater when they are experiencing life outdoors.

Spending time in nature relieves stress - heart rate, blood pressure, cortisol levels and perceived stress are all reduced following exposure to nature. The experience also affects mood, emotions and feelings, causing a reduction in negative emotions and an increase in positive ones. These effects hold true for people with anxiety and depressive mood conditions, where being in nature has been associated with relaxation and reduced stress. The evidence is overwhelming - spending more time in nature is beneficial for mental health.

The impact on children is worth highlighting. Studies have shown that exposure to ‘greenness’ around the home is linked to lower risk of depressive symptoms among young adolescents. Adults who had high levels of childhood nature exposure have significantly better mental health than those who had low levels of nature exposure growing up.

Indirect benefits through nature

There are other, less obvious, ways that nature can improve mental health, too. For example, nature opens the door to opportunities like social engagement and physical activity. Time in nature can take us away from noise and air pollution, and move us out of the sitting position. The provision of green space in urban areas increases the amount of social contact a person has and can boost the sense of community, both of which are important for mental well-being.

The physical activity element is particularly important. Access to green spaces promotes physical activity as it offers an attractive place to exercise - be that going for a walk, run, cycle or skate. People who live closer to parks are more likely to reach their recommended activity levels. This impact is even greater for children, whose activity levels soar when they are taken to green spaces.

The pathway has far-reaching benefits - the increase in physical activity levels promoted by green space could reduce obesity in both children and adults. Given that people with obesity are at higher risk of developing mental health issues, like depression, access to green spaces could improve population-level physical and mental health in the long-run, too.

Another determinant of mental well-being is sleep. Much of the global population don’t get the recommended eight hours of sleep every night, and a lack of sleep can contribute to mental health problems. While the link might seem unlikely, exposure to green space can influence sleep. Green spaces can act as a noise buffer, preventing sleep disturbances, and studies have shown an association between green space exposure and improved sleep quality.

Biodiversity as a relevant factor

Most of the studies into the benefits of green space on well-being have been just that - without any focus on the level of biodiversity (the variability among organisms) in the natural spaces. But the number of scientists looking into the idea that heightened biodiversity might have a positive impact on mental health is on the rise; it’s an important topic and the results could be beneficial for both human health and biodiversity conservation.

Species diversity on a local and city level can have positive effects on mental health; higher bird and plant species richness in urban parks, for example, has been linked to improved psychological well-being.

The effect of microbes

Some scientists have suggested that biodiversity might have another effect on mental health - through biophysiological mechanisms. Studies have shown that the gut microflora can have an impact on neuropsychiatric disorders, including depression, anxiety, dementia and multiple sclerosis. Spending time outside increases our exposure to microbes, and the more diverse the green space, the more diverse the range of microbes we come into contact with.

Scientists believe that this exposure to biodiversity might be partly responsible for the benefits of exposure to green spaces in these patients. The theory is known as the biodiversity hypothesis and, while more research is needed to confirm its effects, the mechanisms have been demonstrated to be plausible.

Nature is always the answer

Spending more time in nature is one of the most influential changes we can make to improve our mental well-being. Research has proven the effects of green spaces time and time again for reducing stress, improving mood, reducing negative emotions and helping reduce symptoms of anxiety and depression. The beneficial effects are the same, or even greater, for children, and the public health benefits of increasing biodiversity and natural spaces in urban areas are clear.