Under Nature's Influence

How viewing nature scenes alters your brain's response to pain

A couple of weeks ago, I published a post on how the brain remembers pain and inflammation, how these brain-encoded memories can be retriggered, and what you can do to rewire them. One of the most important facts about pain that I stressed in this post - and that I always discuss with clients who are experiencing pain - is that all pain is produced in the brain. That is, pain is an output of our brains, that results from the brain's mental and emotional processing of various inputs, as illustrated below:

Overview of ascending pathways of pain perception. Source

In the case of acute pain (that is, pain of sudden onset, associated with injury or illness), those inputs originate from specialised sensory receptors called nociceptors, which are activated by noxious stimuli. A noxious stimulus is anything that could cause tissue damage, such as mechanical pressure, irritant chemicals (including those released by damaged cells) and excessive heat and cold. As previously discussed, pain is a warning mechanism that prompts us to withdraw from noxious stimuli when we've been injured, in order to prevent further injury.

Sometimes, however, we need to be able to tolerate acute pain in order to experience a desired outcome. Dentists, remedial massage therapists and athletes know all about this!

Last week, a team of British, Austrian and German researchers published a fascinating study which found that people report less intense acute pain from a noxious stimulus - in this case, electric shocks - when viewing scenes of nature compared to urban and indoor scenes. You're probably thinking that looking at nice scenery makes people feel better so they're not as bothered by pain, but that's actually not how the nature-induced pain relief works. More on that, shortly.

Natural pain relief

Studying the analgaesic effects of viewing natural scenes might sound a tad woo-woo, but this line of research actually has quite a pedigree. Back in 1984, Roger Ulrich reported that patients who had undergone surgery to remove their gallbladders - a procedure associated with considerable postoperative pain - recovered faster, and took fewer and less potent analgaesics, if their hospital room window offered a view of trees rather than a brick wall.

Ulrich's intriguing paper kicked off a slew of subsequent research which has explored the ability of various forms of nature exposure to relieve pain in diverse settings. However, most of these studies have not had adequate control conditions, and they have relied on self-report measures of pain which makes it impossible to identify whether nature-viewing impacts the 'lower-level' sensory aspects of pain (nociception and its neural processing) or the 'higher-level' components (affective or emotion-related, cognitive or thinking-related, and motivational processes, and their associated neural responses).

To circumvent the limitations of previous studies, the research team behind the new paper came up with a rather ingenious experimental design: Volunteers were placed in a functional magnetic resonance imaging (fMRI) scanner, and were administered small electric shocks to the back of their left hand while they watched videos of a natural scene, an urban scene and an indoor office scene, all accompanied by matching soundscapes. The urban scene was deliberately constructed to be aesthetically appealing through the inclusion of natural elements (a lake and trees) so as to rule out the possibility that viewing an ugly, chaotic scene might confound the experimental results by actually exacerbating pain.

After viewing each scene, participants were asked to rate both the intensity of the pain from the shocks and its unpleasantness, to help differentiate between the lower-level nociception and sensory processing aspects of pain, and the higher-level cognitive-emotional and motivational aspects. As anticipated, self-reported pain was lower when participants viewed the nature scene than either the urban or indoor scenes, with no difference in pain ratings between the urban and indoor. Participants reported a greater drop in the unpleasantness component of pain than the perceived intensity. These findings would tend to suggest that viewing nature scenes impacted higher-level pain processing more than lower-level. This makes intuitive sense; I think most people would assume that looking at a peaceful, engaging natural scene would make you feel happier and more relaxed, so you would feel less disturbed by pain.

But when the researchers turned to the fMRI scans to analyse signatures of connected neural activation in multiple brain regions, known as multivoxel patterns, they found something quite different: viewing nature scenes decreased the neurologic pain signature (NPS), which captures processes connected to nociception and lower-level sensory processing, but it did not affect the stimulus intensity independent pain signature-1 (SIIPS1), which captures variance in pain that is shaped by emotional and cognitive (higher-level) processes.

That is to say, contrary to what participants actually said about how viewing the various scenes affected their experience of pain, their brain activity revealed that viewing nature scenes didn't modulate the way they were thinking and feeling about the pain induced by the shocks - which, incidentally, is how placebos appear to work. Instead, it changed the way their brains interpreted nociceptive signalling - that is, information about the shocks transmitted from nociceptors up to the brain. In effect, viewing nature scenes 'dialled down' those signals so that they were less intense before they even reached the 'higher' parts of the brain that are involved with thoughts and emotions.

Participants also reported that they felt that viewing the nature scene help to distract them from the shocks or tolerate them better than either the urban or indoor scenes, and in this case, the fMRI scans confirmed their impressions. When viewing the nature scene, participants had greater activity in a neural circuit that is involved in modulating pain by diverting attention away from it. As the researchers noted, this finding lends support to the attention restoration theory (ART) of the connection between nature and health:

"ART suggests that natural stimuli can restore depleted attentional capacities⁹. The reasoning behind this argument is that nature possesses many features that are softly fascinating to humans and engage us in a distracting but not overly demanding manner. In the context of the experience of pain, ART would imply that features of the nature stimuli divert attention away from the painful sensation."

Nature exposure induces analgesic effects by acting on nociception-related neural processing

Interestingly, participants who stated that they felt more psychologically connected to nature did not experience any greater reduction in pain when looking at nature scenes, than participants with lower nature connectedness. So even people who prefer the buzz and bright lights of the city to the peace and quiet of wild nature, still get pain relief from looking at nature scenes, but not from looking at an aesthetically pleasing urban landscape. And this finding provides further evidence that the analgaesic impact of viewing nature scenes is not due to the placebo effect - that is, to people’s beliefs and expectations that nature is 'good for them'.

All very interesting, but so what?

Yeah, so all this is quite fascinating (at least to nerds like me), but what relevance does it have to our lives? Plenty!

The first, most obvious implication is that any professional whose occupation involves inflicting pain on other people, should consider investing in technology that allows their patients or clients to view nature scenes while they're carrying out their work (BDSM dominatrixes excepted; their clientele is a whole other ball of wax). If you're a dentist, a rehabilitation specialist or a surgeon who performs procedures under local anaesthetic, your patients will be able to tolerate treatment with less pain relief, if they can view nature scenes while you're working on them. (The researchers found that the pain-relieving effect of viewing nature scenes was about half the magnitude of that from painkillers.)

I've experienced this first-hand. A couple of years ago, I had to have lengthy and highly invasive periodontal surgery. Luckily, my surgeon had a ceiling-mounted screen which played aerial videography of beautiful natural locations, throughout the entire arduous procedure. Every time I felt like jumping up and running, screaming, from the room, I consciously directed my attention to the nature scenes which helped me find new reserves of pain tolerance. (By contrast, my regular dentist just plays TV shows, which are so annoying I'd rather keep my eyes closed for the whole appointment.)

Athletes whose training involves pushing themselves through pain barriers should also take note. Training in nature is ideal, but if you can't, you may find you can complete that extra five Ks on the treadmill or rowing machine, or punch out the final two reps, much more easily if you're watching nature videos or looking at a photo of a nature scene.

The second implication is that people who are suffering from acute pain from an injury, illness or surgery, can reduce their need for pain medication and thus their risk of running afoul of opioid dependency or toxicity from NSAIDs or paracetamol, by watching nature videos during their recovery; try the 4K Video Nature YouTube channel to get you started.

The third implication is that these findings may also have relevance to the management of chronic pain. As the authors put it,

"Considering the severe impact chronic pain has on patients and our society and the potential risks associated with its pharmacological treatment, nature exposure represents an interesting complementary pain management strategy. While the current study provides first evidence as to which underlying processes are altered in the processing of acute pain, chronic pain is characterized by complex and multifaceted changes in psychological and neural processing⁴³ that only partially converge with those during acute pain. It is an exciting research avenue to test the generalization of the present findings to chronic pain and the potential alleviation of chronic pain conditions."

Nature exposure induces analgesic effects by acting on nociception-related neural processing

The fourth implication is more speculative. With my evolutionary psychology hat on, I see the reduction of acute pain from viewing nature scenes as evidence of sensory, cognitive and emotional adaptedness to the shapes, colours and movement patterns of the natural world. When deprived of exposure to the natural world, we become less resilient, both physically and psychologically. If exposure to nature buffers us against pain, as this study suggests, then the lack of regular contact with nature which occurs in urban environments, would cause us to lose that buffer so that we become more sensitised to pain.

And bearing in mind that psychological and social pain is experienced exactly as if it were pain generated by physical damage (as discussed in Your brain on pain), perhaps the explosion of so-called mental illness in our young people is at least partially attributable to the fact that so few of them grew up playing outside in nature, as was the norm in earlier generations, including mine.

While further research is, as always, needed to confirm the findings on acute pain and explore the effects of virtual nature exposure on chronic and psychosocial pain, I don't have any hesitation in recommending that people who are in any kind of pain just go ahead and try it out - there's absolutely no down side!

Getting out into actual nature is even better, of course, as there are benefits such as fresh air and sunshine, enrichment of your microbiome, and exposure to immune-boosting phytoncides that you're not going to get from just watching nature scenes on a screen. But for hospital patients and people undergoing painful procedures or recovering from injuries - as well as city dwellers, office workers, and anyone else who just can't get out into nature as often as they would like - viewing nature scenes is a non-toxic, non-addictive, and easily accessible strategy to help ease the pain of life.

For information on my private practice, please visit Empower Total Health. I am a Certified Lifestyle Medicine Practitioner, with an ND, GDCouns, BHSc(Hons) and Fellowship of the Australasian Society of Lifestyle Medicine.