Since life began, organisms needed some way of seeking out things that are good (food, light, warmth, a mate) and we’ve developed senses and systems to give us pleasure when we find these things. Think of the way you feel when you get in the shower after being soaked to the bone, or your first bite of food after fasting.

The flip side of this is that (again right from single celled organisms on up) we need to have some way of avoiding harm. The taste of something poisonous, the smell of putrid meat, the pain of putting your hand on a stove.

Pain has developed as the master protection mechanism to help us to grow and develop, avoiding things that might kill us or harm us along the way. Unfortunately, it has become so very good at doing this that there are lots of reasons our system can become sensitised, and therefore over-protective from things that are really not harmful at all. After spraining an ankle, the area further down your foot starts to hurt just from light pressure, as does further up the leg. Why might this happen when those distant tissues are not actually damaged? Sensitisation by inflammatory products. This is a helpful adaptive response that forces you to change your behavioiur – ie you leave your foot and leg alone, and let it get better.

The problem comes, though, when sensitisation occurs in ways that are not protective or helpful. Think of a back injury that occurred three years ago – the tissues are all healed already, why is your system still causing you to tense up, breath hold, keep your back as stiff as a board if those behaviour changes are not helping your back heal? What about people who have Rheumatoid Arthritis? Their joints can become totally non-functional due to pain, but this is not helping them avoid harm or recover from injury – instead their immune system is secreting inflammation, which sensitised their tissues in their joints so that even small amounts of bending or gripping cause extreme discomfort. For more information about this, read this blog.

Picture of arthritic hands showing pain in joints

In the last few years we’ve started to understand more about how many different ways the nervous system and immune system can collaborate to cause increased protection, and there are a myriad of ways the system can become over-protective. Your brain, too has an incredibly active role in increasing or decreasing the protective response, based on what it considers dangerous, or threatening.

For instance, in certain lab experiments, people universally reported higher pain levels if they had were shown a red light while having a stimulus applied to their skin than if they were looking at a blue light.

Here are some other strange facts;

  • You will have more severe pain if you are exposed to something that smells awful while you’re hurting yourself, than if you’re smelling something really pleasant

  • If you’re bending over with a sore back, it will feel stiffer if you hear the sound of a creaky door than if you hear whooshing airy noises

  • If someone has a painful knee and looks at a simulated leg in VR goggles being elongated and stretched while their real leg is gently tugged, the pain reduces

  • Imagining yourself doing exercises in a gradually increasing manner can reduce sensitivity (Graded Motor Imagery), and even watching someone else doing movements that you find challenging can help to retrain a sensitised brain (Motor Empathy)

  • Telling yourself things like “I’m ready for the scrap heap / my bones are crumbling” will cause increased attention from your brain and nervous system to that part of your body, causing inflammation and immune activity, which actually causes them to wear faster!

  • If you watch someone get a pin poked into their hand, the part of your brain that would cause you to have pain in the back of your hand fires.

    • However, if the person you’re watching get pricked has a different coloured hand from you (racial outgroup) it doesn’t happen nearly as much or not at all

  • People can experience pain in parts of space that their body doesn’t even occupy (see rubber hand illusion on Youtube)

  • Sensitivity can become so bad that even a breath of wind or light touch of clothes can be unbearable

So as you see it is an incredibly powerful protection system, that does us a whole lot of good, and we’d die early without it – but you don’t always have to trust that it’s a direct reflection of what’s going on in your body. Stress, sleep, nutrition, past experience, culture – all of these have an enormous effect on how protective YOUR pain system is.

If any of this makes you think your system might be a bit over-protective and you’d like to know how to reduce this sensitivity, and live a full life (even in the presence of some pain) give us a call and we’ll have a good chat.

Ben Kewish

*Article originally published in Emerald Messenger