• 2-5 Hours in Nature each Week Improves Brain Health

    On the basis of an analysis of nearly 20,000 people’s feedback, a recent paper concluded that just two hours of outdoor recreation per week is sufficient to yield a significant improvement in health or well-being, compared to people who get no recreation time in green spaces at all. In fact, the more time people spent engaged in outdoor recreational activities, the more happy or healthy they reported to be; an effect that peaks somewhere between 200-300 mins of weekly exposure to mother nature.

    Many previous papers have reached similar conclusions. A meta-analysis of 21 studies suggested that a person’s chances of developing a mood disorder were increased by 28% if they lived in urban as opposed to rural areas, where nature is more easily accessed. There are of course other possible explanations for urban dwellers being more likely to encounter mental health issues than rural ones. Perhaps humans are just more vulnerable to such disorders in a densely as opposed to sparsely populate environment? Or is it really something to do with the presence of trees in the environment?

    This possibility has been addressed by studies using high-resolution satellite imagery to plot tree density against various measures of well being in a huge sprawling urban area in Toronto, Canada. One such study (by Kardan et al, 2015) concluded that people who lived in an area with a higher density of trees in their neighbourhood had a significantly higher perceived health level and a lower incidence of cardio-vascular conditions.

    This complements the earlier study mentioned above that compared the mental health outcomes of people who moved from more green to less green urban areas and vice versa. Alcock and colleagues analysed 5 consecutive years worth of data from 1,084 British households, finding that those who moved from less green to more green urban areas enjoyed fewer mental health complications over the following three years.

    In a previous blog I described the classic study of patients who were recovering from a straightforward hernia operation in adjacent rooms, one that had a view of a brick wall and one that had a view of a small patch of grass with a tree growing in it. The patients who ended up in the room with the view of the tree recovered faster (as evidenced by the number of days they stayed in hospital post-surgery) and even required lower doses of analgesic medication to help them cope with the pain. Other studies have gone on to suggest that just being able to look out the window to catch sight of a slice of mother nature reduces aggression and criminal activity.

    So what is is about plants and trees that seems to have such a profound impact on how we feel? Hartig et al (2016) suggest that viewing a natural scene helps us to put things in perspective, to create a healthy psychological distance between the day-to-day grind by actively engaging our attention in features of the natural landscape. This can help us to repeatedly gain the positive and reinforcing experience of feeling our mood lift and stress subside, both of which naturally occur when we turn our back on the hectic urban world and engage with the more relaxed pace typical of open green spaces. Beyond these important factors, trees also improve air quality and aesthetic appearance of an environment.

    Across many studies, having access to green spaces has been shown to promote mental health, reduce accidental death and even mitigate against the negative impact of economic struggles on various health measure. It also reduces blood pressure and stress by promoting physical activity and reducing sedentary leisure time.

    Even before I read all about this body of research attesting to the physical and mental health benefits of spending leisure time in natural settings, my behaviour over the last few years suggests that I knew this innately. Since I moved into my flat a few years back I’ve spent countless hours watching our neighbourhood sparrows, blackbirds, blue tits, goldfinches, crows and wood pigeons flitting around the communal gardens (see above) that I can see from my balcony. When I taking breaks from researching and writing books and blogs while surveying this green scene, I can feel the stress drain out of my body. Then when I get back to work, I feel significantly better able to crack on after the ten to fifteen minutes spent watching the natural world do its thing; an observation supported by research indicating that attention and memory resources get a boost from even a brief exposure to nature.

    Beyond engaging with mother nature as a spectator, one of my favourite recreational past-times is to go running around Richmond Park with my mate Nathan. We’ve been doing it once a month for the past eight years. We talk almost non-stop during these 10km runs, mostly about nonsense just to reduce our perceived exertion (i.e. to distract ourselves from the bodily discomforts of keeping up a brisk jog for a solid hour), but we also regularly find ourselves commenting on how life just seems much better, easier, less daunting when you get outside, running cross-country through woods, fields of fern and grassy plains studded with herds of deer. It seems that the academic research data supports these views and backs the idea that communities benefit hugely from improved access to green spaces.

    In addition to these monthly brain blogs, I regularly tweet about the latest neuroscience research to hit the lay press and review a virtual reality game or experience every week on my YouTube channel Brain Man VR.

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  • Health Benefits of Parks vs Anti-Social Behaviour by Dr Jack

    Dr Jack is on The One Show on Mon 1st Aug 2011 at 7pm

    What do green spaces (parks, fields, commons etc.) do to the human brain? Why do people drop litter? How does visible evidence of anti-social behaviour affect the way other people behave? How would people behave if those responsible for keeping one of London’s finest Royal Parks clean were to down tools for an entire weekend?

    All of these questions were asked of Dr Jack by The One Show reporter Justin Rowlatt in Hyde Park where the Keep Britain Tidy campaign ran an interesting experiment over the weekend to see how people would react if the rubbish they dropped was left to accumulate. This brainpost details some of the background to Dr Jack’s comments on The One Show (Mon 1st Aug, BBC1, 7pm).

    Spending time in green spaces reduces blood pressure, increases self-reported happiness ratings and even boosts self-confidence. And this is not just because being in clean and tidy natural environments encourages people to take exercise. Neither, it seems, do you have to actually be physically outdoors in these spaces to benefit from these life-enriching effects. Merely having a view over a natural green space is sufficient to influence the rate of healing and the perception of pain. In a famous Science study published in 1984 by Roger S. Ulrich, patients whose recovery room had either a view of a small copse of trees or a brown brick wall were compared, retrospectively, in terms of duration of their stay in hospital and strength of analgesia required to deal with the pain induced by gall bladder surgery performed in the same Pennsylvanian hospital. They found that on average those with the view of a green space spent on average one less day in hospital and required much fewer moderate or strong doses of pain killers compared to those with a view of the brick wall.

    Getting out in green spaces is good for your mood AND your health (image courtesy of Nuttakit)

    Numerous studies have been conducted since to try to establish what aspects of the natural environment have the strongest benefits to our wellbeing. Virgnia I Lohr, of Washington State University, describes studies suggesting that bright green colours synonymous with luscious vegetation make us feel happier than light greens and yellows that could indicate plant nutrient deficiencies. Furthermore not only does mood improve when we look at trees but we even have a preference for trees with spreading canopies over short and stubby bush like trees typically found in arid areas and tall / narrow trees typically found in areas of very high rainfall. The explanation Lohr offers for these preferences for bright greens and trees with spreading canopies is that such visual stimuli are indicative of conditions suitable for the proliferation of human life. In other words an innate appreciation of such visual characteristics conferred a survival advantage to early humans as they would have been attracted to environments with flourishing plantlife and thus food sources, whilst others would have perished in environments that were either too dry or to wet.

    Parks and open spaces are clearly very beneficial in terms of improving health and quality of life. However if it wasn’t for the armies of park staff who clean up after members of the public who routinely leave their litter behind, these green spaces would soon become the last place you would want to spend your spare time. The question is, why do people leave their litter behind for somebody else to clear up? All human behaviour is governed by predictions of reward and punishment. We are subconsciously guided towards behaviours that maximise rewards whilst minimising punishments.

    Will people keep Hyde Park tidy when the cleaning staff down their tools for a weekend?

    The pleasure pathways of the brain, in particular the nucleus accumbens, are involved in attaching a reward prediction to a certain course of action based on past experience. Drinking water when thirsty or eating food when hungry are examples of behaviours hardwired to produce powerful sensations of pleasure because they help to keep us alive. However the sense of pleasure that people get from putting rubbish in the bin is not innate, like drinking and eating, but instead it must be learned. Nonetheless, even in the absence of a sense of reward from putting rubbish in the bin, if littering is consistently punished then that too can steer people away from anti-social and towards pro-social behaviours. Whilst most parents are still apt to discipline their children for littering, which provides valuable experience of the punishments that follow such anti-social behaviour, parents aren’t always around. In the past adults felt at liberty to scold, or even physically punish, any child that they happened to see dropping litter, but in the modern climate of political correctness this is becoming a thing of the past. Young people no longer learn that punishment reliably follows the act of dropping litter and so their brains do not generate the sense of discomfort, anxiety or unease (generated by the anterior insula) that would precede acts of anti-social behaviour that they know through experience is likely to be punished. So in the absence of any negative emotions associated with the act of littering, nor positive emotions associated with the act of putting litter in the bin, rubbish ends up being lobbed around willy nilly, even when a bin is conveniently located just a few steps away.

    When children are brought up with a strong sense of social responsibility then in later life they may get sensations of what might be called “righteous” pleasure from doing the “right thing.” The point is that to get a feeling of satisfaction from performing pro-social behaviours you must have been trained over prolonged periods of time by parents, carers, teachers and/or peers in order to get a kick out of it. If society wants to encourage pro-social behaviours we’ve either got to praise young people more for putting litter in the bin, or make them very uncomfortable when they just drop it for someone else to deal with.

    A fascinating study, again from the journal Science (Keizer et al, 2008), indicates that evidence of other people’s antisocial behaviour can make others more likely to be antisocial themselves. This would suggest that the problem with litter goes beyond just rubbish on the streets and in our parks. In one of their experiments they demonstrated that environments in which anti-social behaviour was evident, e.g. litter strewn around on the pavement, graffitti sprayed on the walls or fire crackers set off in the background, not only makes people more likely to litter themselves, but also to commit more serious anti-social behaviours like theft. It seems that people modulate their own behaviour according to cues regarding the degree of anti-social behaviours committed by others.

    It is for this reason that Dr Jack predicted that whilst Hyde Park is pristine and clean people will be (slightly) more likely to put their rubbish in the bin. However as the rubbish builds up people will probably become more and more likely to leave their rubbish behind. Furthermore, based on the findings of Keizer and colleagues, the more the rubbish builds up, the more likely people will be to commit other forms of anti-social behaviour. To find out if Jack’s predictions were right, tune into BBC1 tonight at 7pm.

    In addition to these weekly brainposts you can follow Dr Jack’s daily #braintweet on Twitter.

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