How being out in nature changes our brains

There’s evidence from psychological studies that nature holds a special place in our hearts and can be a powerful mental health elixir: immersion in the great outdoors, and in wild country like you find in many national parks, seems to leave participants feel re-energised and mentally refreshed. But is this just down to digitally detoxing - divorcing ourselves from mobile devices and social media - or is there something else going on? What does the science say? David Pearson is a cognitive neuroscientists at Anglia Ruskin University…

David - It can take a number of different forms. Generally reduction in stress, people have a greater sense of positive emotion. Studies have also shown that people report lower symptoms in terms of anxiety and depression after spending time in nature. And we also see general improvements in cognitive functioning. Things like better sustained attention, better ability to concentrate, better ability to solve complex problems and things like that.

Chris - Do you actually have to be there to get the benefit or can you stay on the couch and tune into David Attenborough and watch a bit of Blue Planet or something and say, 'well, I've immersed myself in that' and get the same benefit?

David - Well, I mean, there is research which shows that looking at videos of nature or even just photographs of nature can have beneficial effects. And there's a growing research looking at virtual reality simulations of nature, also showing that they can have beneficial effects. In terms of what the added benefit of being in a real environment is. One is complete immersion and the other is that being in nature, it's a multi-sensory experience. So if you're just looking at David Attenborough that's predominantly visual and auditory. When you are in a real environment, you've got the visual stimulus, but also the sounds of nature, bird song, the wind, and so on. Also just the wind on your skin, the temperature. So it's a more immersive experience and you have a greater sense of being kind of removed from the stresses of your everyday life.

Chris - I suppose there's a physical element too, isn't there? Because if you're out and about in the country, you're going to be more active and we know that activity also has a positive reinforcing effect on mood and everything.

David - Absolutely. I mean, I think it's not just the exposure to nature, it's also the exercise. It's being in a less polluted atmosphere, being in a generally calming environment. So you get a number of different factors, which we know individually can be beneficial and which are combined when in somewhere like a national park or an area of outstanding national beauty.

Chris - What sorts of experiments can we do to probe this? Because it's hard to take a brain scanner up the top of a mountain in the Lake District, for example and get an objective measure of what's going on in someone's brain. So how have people sought to kind of understand this apart from just asking people vague questions?

David - I think some of the best research is intervention based studies. So basically you take at least two groups of people. You measure their stress and their cognitive functioning, and then one group you get to do a kind of nature based activity and another group you get to do an equivalent built environment activity. And then you measure their levels of stress and cognitive functioning again. And there's a growing number of studies which have done that, which have found that when people do take part in a nature-based activity, and if you compare them to another group who've done the same kind of activity in a more built environment, they show improvements in terms of reduced stress, enhanced cognitive functioning and things like that.

Chris - How long do the benefits last?

David - The benefits do last. It's not just for when you're in nature. So studies have shown that if you come back from a walk in nature and you compare that to someone who's had the equivalent length of walk in, say, a built environment that people are better at concentrating, say the studies with students showing that they pay more attention in lectures and that you have a sustained mood and sustained improvements in things like attention and concentration, which can last beyond just a period in which you are in that environment.

Chris - Is there a physical mechanism if we, based on our understanding of the way the brain is wired up and the measurements we can make practically and objectively on people who take part in these sorts of studies, is there some kind of mechanism we can attribute to why we see this positive effect of being out in nature?

David - As you said earlier it's quite difficult to get a detailed look at the functions of the brain due to when people are in real environments, of course we can't take a scanner up a mountain and not put it in the forest. So a lot of that research is focused just on looking at how the brain activity when people are looking at, for example, photographs of natural and built environments. Now even with that limitation, it's shown that the brain does respond differently when we're just looking at photographs of natural environments versus built environments. So we see changes in the twin or default attentional network in the brain, which is a part of the brain when we are kind of paying more attention to our internal mental thoughts rather than the external world. And we also see differences in the kind of the attentional parts of the brain, which, for example, look at the location of objects or what objects look like. Those are the dorsal and the ventral attentional networks. So this kind of ties into a theory that one reason why natural environments are beneficial is because the way in which our attentional systems of the brain engage in natural environments is different to when we're in a built environment. So when we're in a built environment, there are lots of elements in that scene which are kind of dynamically competing for our attention. And when we're in a natural environment, we're still paying attention to it when it's a much more relaxed, less dynamically externally driven way. And this is one of the reasons why we get a reduction in stress and an improvement in cognitive functioning after we're exposed to nature.

Chris - Is there a difference between an older person who doesn't effectively go digital cold Turkey when you divorce them from a mobile phone and access to Facebook and put them in that environment? Compared to a young person who, as far as I can tell, their phone has become an extension of their body and you put them in an environment where there is no signal. Do one group over the other tend to benefit more or tend to find it a better experience than the other?

David - Most research shows that lots of different demographics benefit kind of age, gender, these aren't necessarily significant factors. One issue is some research has shown that the amount of time you spent when you were growing up in a natural or built environment can be a mediating factor. So one study showed that the amount of time you'd spent in a natural environment in the first 15 years of your life was a factor in terms of how restorative you found spending time in nature or spending time in built environments. So your childhood experiences in nature could be a factor in how restorative you find natural environments. And that is a concern because as you said, with digital technology, younger generations are spending less time in natural environments than previous generations.