Ever since I was young, feelings of melancholy or listlessness have inevitably given rise to a particular craving: to go outdoors. The urge has taken on different forms – sometimes I want to walk the clifftops by a tempestuous sea and have my face scoured by the salty wind; other times I want to lean back against the trunk of a venerable tree and look up at the golden sun shining down through its green leaves – but, no matter how it manifests, this desire has been a constant companion over the decades. Like a good friend who brings you soup when you have the flu, that companion has consistently helped me get through difficult times: when I return home after my dose of nature, I inevitably feel emotionally healthier and more balanced.

After years of thinking that my impulse to self-medicate with green spaces was a quirk of my own personality, I recently came to discover that it is actually a habit shared by many, and its value is documented by an increasing body of scientific evidence. Exposure to nature really is good for you, not just mentally but also physically; benefits are observed across all demographics, habitats, activities, and lengths of immersion studied thus far.

If you’re looking for testimonials on the value of a ‘nature fix’, as it is called by author Florence Williams in her book of the same name, you could read one of the many recent books on this topic – including Joe Harkness’s Bird Therapy, Sarah Ivens’ Forest Therapy, Emma Mitchell’s The Wild Remedy, and Wallace J. Nichols’s Blue Mind. These and  other similar volumes could be said to be descendants of Biophilia, a 1984 book in which biologist and conservationist Edward O. Wilson proposed that humans have an innate desire to ‘affiliate with other forms of life’— and suggested that we benefit from doing so.

Alternatively, if you would like more specifics about how to actually administer a green therapy, look no further; the following paragraphs detail the what, who, and why/ how reported in the scientific literature to date.

What are the health benefits of nature?

Humans have probably been deriving health benefits from the environments in which we live for as long as Homo sapiens has been a species. For example, some of our most commonly used pharmaceuticals come from nature: aspirin is derived from willow bark, and the antibiotic penicillin is derived from the penicillium mould.

However, biophilia is most frequently discussed in relation to mental wellbeing, and one of the best-known early natural treatments is sea bathing, prescribed by doctors in the 18th and 19th centuries to combat ‘melancholy’ or ‘spleen’ (i.e., depression). These same physicians also saw the value of the fresh, clean air of mountaintops and deserts, where tuberculosis patients could retreat to sanatoria to recover their vigour and extend their lifespan. Sanatoria were no longer needed once anti-tuberculosis medication was discovered, but by then researchers had already confirmed that there were genuine benefits to spending time in these natural environments – for example, because sunlight can kill harmful bacteria and stimulate tissue generation.

Recent studies have also shown that mortality rates— particularly those from cardiovascular problems—are lower in green environments than in those where nature is less prominent. This is likely related to the fact that both blood pressure and heart rate tend to be healthier in more natural spaces; it probably doesn’t hurt that greener environments generally also protect against asthma and allergies.

Anyone who has gone on an extended camping trip will be familiar with the way that exposure to natural habitats alters sleeping patterns; though those first couple days of waking at sunrise might come as a shock, the body seems to quickly adjust to the new rhythm, leaving you feeling more rested and energised. This has been formally documented, as has the fact that views of nature – even just glimpses through a window, scenes in a video, or artwork on walls – can speed healing, boost your mood, and increase self- esteem. Interactions with nature also facilitate cognitive function, reduce feelings of stress, and enhance your sense of happiness and wellbeing.

Unsurprisingly, given this extensive suite of positive reactions and characteristics, nature is also known to boost creativity – not just inspiring art, as in the case of writers and painters who become prolific during countryside retreats, but also facilitating the sort of ‘eureka!’ moments that lead to major innovative and philosophical breakthroughs (after all, Newton was supposedly sitting under a tree when he developed his theory of gravity). That said, nature is not just a mental stimulant; proximity to nature also seems to inspire people to be more physical, prompting an increase in activities such as hiking, swimming, foraging, and, birding – all of which have been shown to have their own positive impacts on physical and mental health.

Who benefits from ‘nature treatments’?

This year, a UK-wide study on exposure to nature found that its benefits could be observed in all people examined – young or old, wealthy or poor, urban or rural, healthy or battling illness, male or female, disabled or not. Nature can help everyone.

One study on people who were moving house found that those who relocated to more natural environments experienced significant improvements in mental health relative to those who moved to new homes in less natural areas. Although the depressed mood did eventually improve in the latter group and return to baseline levels, the former group continued to experience the positive boost for an extended period of time. In a separate project conducted in the UK, scientists found that people who live near the coast are healthier than those dwelling inland – a pattern that cannot merely be explained by increased levels of coast-related exercise (e.g., swimming or kayaking). Thus, it appears that individuals can benefit not only from living in natural areas, but also from living in particular types of habitat.

Attitudes towards, and expectations of, habitat can also play an important role in how people respond to it. Individuals with extensive experience in rugged, remote environments may find urban green spaces lacking; there are also some cultures  in  which  negative  associations with natural environments may  prevent  enjoyment  of these spaces (though perhaps people may experience benefits of which they are unaware). City-dwellers with no exposure to the countryside may feel overwhelmed in the wild, and anyone who has had a traumatic experience in nature – being bitten by a snake, perhaps, or suffering a terrible allergic response to a plant – may find it difficult to relax in natural environments ever again. That said, it is possible that everyone may experience benefits from exposure to green spaces, even if they are unaware of these perks at the time.

People who are able to recognise biodiversity can get more enjoyment and benefit out of spending time in nature. This effect can be observed even if the biodiversity is perceived rather than actual, and even if that diversity includes non-native species; this likely helps explain why some people get as much benefit from spending time in managed gardens as others derive from visiting a forest.

No matter where you go and what you encounter there, you may get more out of the experience if you are in greater need; research has shown that more mentally fatigued individuals anticipate more effective natural cures, leading to a sense of restoration. Indeed, a growing body of research has shown that green therapies are particularly helpful for those who are busiest, most stressed, and most unhappy – for example, children and young adults with ADHD as well as those who are otherwise neurotypical but are still worried about things such as school exams, adults with high-pressure jobs and packed schedules, and individuals who are feeling lonely. These are all aspects of the personal experiences documented in Emma Mitchell’s The Wild Remedy, in which she describes the way in which nature acted as a lifeline when she needed it most.

People who are able to recognise biodiversity can get more enjoyment and benefit out of spending time in nature. This effect can be observed even if the biodiversity is perceived rather than actual, and even if that diversity includes non-native species; this likely helps explain why some people get as much benefit from spending time in managed gardens as others derive from visiting a forest.

Why/how does nature heal us?

Generally speaking, time spent in nature is time spent away from stressful, sedentary, or otherwise harmful activities – and this goes a long way towards explaining many of the benefits of green therapies. However, nature is not helpful just because it is not something else; exposure to natural environments also impacts our health by altering physiological processes.

For example, plants act as natural filters, removing pollution from the air and leaving us with cleaner oxygen to inhale. Engaging in slower, deeper breathing tells the body that it can stand down the sympathetic nervous system – the one responsible for ‘fight or flight’ – and can instead allow the parasympathetic system to take over; the parasympathetic facilitates what has been known as the ‘feed and breed’ and ‘rest and digest’ groups of behaviours which are, on the whole, less stressful and more relaxed.

Deep breaths also result in increased oxygen intake, which helps balance out levels of serotonin – a neurotransmitter that impacts, among other  things, mood, memory, and social behaviour. The air in natural spaces tends to have higher negative ion counts, which increases brain wave amplitude and facilitates alpha  brain waves that give rise to a clear, calm feeling. Further, the natural landscape is filled with fractals, shapes in which the features of component parts match, when scaled up, the features of the overall shape; these are also described as ‘self-similar’. Looking at fractals can be very pleasing, which researchers now know is because these shapes interact with our visual processing system in a way as to activate the parahippocampus – an opioid-rich part of the brain that plays a role in regulating emotions. Nature also engages our other main externally-focused senses, simultaneously delivering stimuli associated with visuals, scent/taste, sound, and touch. In the modern world it is increasingly rare for an experience to provide so many sensations all at once – or for us to be in a position in which we are actively concentrating on them all. Scientists have found that the types and amounts of stimuli in natural environments provide a Goldilocks- style experience: not so dull as to be boring, not so overwhelming as to be stressful, but perfect for keeping us engaged in a relaxing way. This balances out cognitive function and prevents any one part of the brain from being overwhelmed, which, in turn, allows our neurons to relax and recalibrate.

The rest of our bodies also benefit from this opportunity to unwind. Exposure to nature  results  in  reductions  in the hormone cortisol. Cortisol levels are also known to drop in response to pleasant-smelling plants like lavender and rosemary; these scents also increase blood velocity to the heart, thus improving circulation. Studies of another aromatic – extracts from the hinoki cypress tree – have revealed why exposure to green spaces can improve immune function: even just a few hours of breathing vaporized hinoki oil has been shown to increase the presence of natural killer cells, a white blood cell integral to our innate immune response.

The hinoki oil treatment described above has also been associated with better sleep and reductions in fatigue. In general, exposure to natural lighting scheme helps reset our circadian rhythms and improve our rest. Sunlight also stimulates the release of dopamine, a neurotransmitter that, among other things, acts in the retina to keep eyes healthy and prevent myopia. Depending on what you do when you venture out into nature, you may also be producing endorphins, chemicals that not only inhibit pain signals but also can produce feelings of euphoria – such as the ‘runner’s high’, which you are particularly likely to experience if your green therapy involves activities such as rock climbing, kayaking, or trail running. Research has also found that spending time in nature can reduce blood flow to the subgenual region of the brain, which is related to feelings of self-wallowing; in other words, even if you don’t achieve a ‘high’, you can perhaps combat a ‘low’ by heading outdoors.

One recent study found that it only takes two hours of green therapy a week to kickstart these processes and help you feel the benefits of what some researchers refer to as nature’s ‘biophysical ecosystem services’. You don’t have to be active during that time, and you don’t even have to undertake all that exposure in a single go. Though the effects of the ‘nature fix’ can be felt almost immediately, it is not yet clear just how long these positive impacts can last; further research will be needed to determine how often you should administer a dose of nature if you want to maximize your health.

The future of nature treatments

Researchers predict that, 30 years from now, some 70% of humans will live in urban spaces – where access to biodiversity and green spaces are often minimal. This is one of the main reasons that nature therapy has recently become such a hot topic; indeed, a majority of studies focus explicitly on urban habitats. Another key driver is the global depression epidemic. Though increasing rates of diagnosis may simply reflect a better understanding of mental health and a greater disposition to discuss it, there is also some evidence that our increased isolation from nature and from each other – both of which have been linked to urbanization and to growing use of technology – are disrupting our brain chemistry and causing unhappiness.

Looking to make anthropogenic habitats more enjoyable, more aesthetically pleasing, and generally better for our wellbeing, everyone from doctors to social workers to city planners have already started implementing projects informed by the sort of research discussed above. Schools create gardens so that students can learn about plants through hands-on, whole-body experiences. Doctors and psychologists prescribe nature walks and community volunteering so that patients get fresh air in circumstances where they are also likely to make friends and grow support networks. Hospitals hang nature-themed art on the walls and provide patients with access to gardens. Prisons create green therapy spaces where the incarcerated can de-stress and regain their calm. Cities pass bills requiring the installation of green rooftops and green walls, and divert funds to the creation of, for example, water features specifically designed to mask the sounds of traffic noise.

These and many more measures have been very successful, though it is important to admit that nature cures aren’t always perfect, or for everyone. For example, the introduction of water features might be aesthetically and aurally pleasing, but they could lead to stagnation and facilitate the growth of unwanted insect populations. In a bid to increase greenery, some landscapers might introduce plant species that cause allergic reactions in humans. Though many people love plants of all shapes and sizes, some can feel crowded and hemmed in by certain types and amounts of vegetation, so it is important to consider not just location, but also structure and makeup of natural areas.

It has been documented that more and larger green spaces tend to be found in areas of higher socioeconomic status, suburbs and up-market parts of cities, whereas inner city communities often live in highly concretised tenements. Future projects could very easily increase this divide between haves and have-nots. It is also somewhat ironic that many conservationists and environmentalists have pushed for an exclusionary approach, which seeks to move people out of natural areas where they have lived in the name of protecting species or habitats. This can only reduce the connections between people and nature, and remove the few benefits that they already receive.

Investigations of ‘nature cures’ are increasing alongside reports of ‘ecoanxiety’ – depression, post-traumatic stress, and anxiety related to climate change and environmental degradation; it is, in the word of one researcher, ‘a chronic fear of environmental doom.’ Many who experience eco-anxiety are nature-lovers who, like me, have spent their lives finding solace and healing in the outdoors and are now worried about the future of the planet.

But perhaps our growing awareness of how nature can positively benefit our own bodies might help spur more people into action; rather than trying to appreciate some distant and hard-to-see process such as nutrient cycling and buffering of floodwaters, people could appreciate the more visceral experience of lower blood pressure or lifted spirits. In other words, perhaps our greater investment in the creation and maintenance of green therapy opportunities for ourselves will facilitate conservation and restoration initiatives that will have positive side effects for wild ecosystems – a nature cure for nature itself.

Caitlin Kight is an educator, communicator, and scientist. She is the author of the natural history book Flamingo and tweets as @specialagentCK.

Kalyani Ganapathy is a children’s books illustrator. She lives in South India and enjoys observing nature. You can see more of her work at www.kalyani- ganapathy.com

 

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