Why is pain so exhausting?

By Michael Henry and Lorimer Moseley

One of the most common feelings associated with persistent pain is fatigue and this fatigue can become overwhelming. People with chronic pain can report being drained of energy and motivation to engage with others or the world around them.

In fact, a study from the United Kingdom on people with long-term health conditions found pain and fatigue are the two biggest barriers to an active and meaningful life.

But why is long-term pain so exhausting? One clue is the nature of pain and its powerful effect on our thoughts and behaviours.

Modern ways of thinking about pain emphasise its protective effect – the way it grabs your attention and compels you to change your behaviour to keep a body part safe.

Try this. Slowly pinch your skin. As you increase the pressure, you’ll notice the feeling changes until, at some point, it becomes painful. It is the pain that stops you squeezing harder, right? In this way, pain protects us.

When we are injured, tissue damage or inflammation makes our pain system become more sensitive. This pain stops us from mechanically loading the damaged tissue while it heals. For instance, the pain of a broken leg or a cut under our foot means we avoid walking on it.

The concept that “pain protects us and promotes healing” is one of the most important things people who were in chronic pain tell us they learned that helped them recover.

In the short term, pain does a terrific job of protecting us and the longer our pain system is active, the more protective it becomes.

But persistent pain can overprotect us and prevent recovery. People in pain have called this “pain system hypersensitivity”. Think of this as your pain system being on red alert. And this is where exhaustion comes in.

When pain becomes a daily experience, it becomes a constant drain on one’s resources. Going about life with pain requires substantial and constant effort, and this makes us fatigued.

About 80 per cent of us are lucky enough to not know what it is like to have pain, day in day out, for months or years.

Whenever you are in pain, you are faced with a choice of whether, and how, to act on it. Constantly making this choice requires thought, effort and strategy.

Mentioning your pain, or explaining its impact on each moment, task or activity, is also tiring and difficult to get across when no-one else can see or feel your pain.

In chronic pain, it’s not just the pain system on red alert. Increased inflammation throughout the body (the immune system on red alert), disrupted output of the hormone cortisol (the endocrine system on red alert), and stiff and guarded movements (the motor system on red alert) also go hand in hand with chronic pain.

Each of these adds to fatigue and exhaustion.

Loss of sleep is also a factor in both fatigue and pain. Pain causes disruptions to sleep, and loss of sleep contributes to pain.

In other words, chronic pain is seldom “just” pain. No wonder being in long-term pain can become all-consuming and exhausting.

Ongoing pain may prevent people working, limit their socialising and impact their relationships. This can lead to a descending spiral of social, personal and economic disadvantage.

There is good news though. Modern care for chronic pain, which is grounded in first gaining a modern understanding of the underlying biology of chronic pain, helps.

Understanding how pain works, how persisting pain becomes overprotective, how our brains and bodies adapt to training, and then learning new skills and strategies to gradually retrain both brain and body, offers scientifically based hope; there’s strong supportive evidence from clinical trials.

The best treatments we have for chronic pain take effort, patience, persistence, courage and often a good coach. All that is a pretty overwhelming proposition for someone already exhausted.

Michael Henry is Physiotherapist and PhD candidate, Body in Mind Research Group, University of South Australia and Lorimer Moseley is Professor of Clinical Neurosciences and Foundation Chair in Physiotherapy, University of South Australia. This article is republished from The Conversation under a Creative Commons licence