Central sensitisation is when the spinal cord and brain become more sensitive and amplify danger signals, so that pain spreads, lingers, or is set off by things that would not normally hurt. It is a change in how the nervous system processes signals rather than a sign of fresh damage, and it sits behind a great deal of persistent pain. The encouraging part is that a sensitised nervous system can settle again over time.
This page is for education and does not replace assessment, diagnosis, or treatment by a qualified health professional.
Part of our complete guide to Understanding Pain
What is central sensitisation?
Central sensitisation describes a state in which the central nervous system, meaning the spinal cord and brain, becomes more responsive to signals from the body, so that pain is produced more readily and more strongly than the situation calls for. The nervous system has, in effect, turned up its own gain.
The clearest way to picture it is a volume dial. After an injury, the dial is turned up for good reason, so that you notice the problem and protect the area while it heals. The trouble comes when the dial stays high long after it is needed. A system left on a high setting starts to treat quiet signals as though they were loud ones, so that a whisper of sensation is heard as a shout. This is why ordinary movements, light touch, or everyday activities can hurt when the system is sensitised, even though nothing harmful is happening.
When pain behaves this way without a clear ongoing source of damage, clinicians sometimes describe it as nociplastic pain, a term the International Association for the Study of Pain uses for pain that arises from a change in how the nervous system processes signals rather than from tissue or nerve damage.
Peripheral and central sensitisation
Sensitisation can happen at two levels, and telling them apart helps make sense of how pain changes over time.
Peripheral sensitisation happens in the tissues themselves. After an injury, the area releases a mix of inflammatory substances that make the local danger receptors easier to trigger and more reactive. This is why a fresh injury feels tender and sore to move. It is normal, it is helpful in the short term, and it usually settles as the tissue heals.
Central sensitisation happens in the spinal cord and brain, where the amplification takes place inside the nervous system rather than at the injury site. The nerve cells that carry danger signals become easier to activate and begin to respond to a wider area than before. Because the change sits in the processing rather than the tissues, pain can carry on, spread, and be triggered by harmless input long after any injury has healed.
The signs of a sensitised nervous system
Central sensitisation tends to show itself through a recognisable set of features. You may notice some and not others.
- Allodynia: pain from something that should not normally hurt, such as light touch, the brush of clothing, or a breeze on the skin.
- Hyperalgesia: a larger pain response than expected from something only mildly painful, so that a small knock produces a big reaction.
- Spreading pain: pain that extends beyond the original area, or that moves around, rather than staying neatly where an injury was.
- Pain that outlasts healing: discomfort that continues well past the time the tissues would be expected to recover.
- Wider sensitivity: for some people, the system becomes more reactive in general, with poorer sleep, lower tolerance for stress, and sensitivity to bright light or loud noise.
These features do not mean a person is fragile, imagining things, or doing damage. They are signs that the processing of signals has been turned up. The pain is produced by a real biological change, and it hurts every time, a point we explore further in does pain mean damage?
Why does central sensitisation happen?
The nervous system is built to protect you, and sensitisation is that protective drive overshooting. When the brain reads a situation as threatening, it can amplify the signals coming from the body so that you act to protect yourself. In some people, and for reasons that are not fully understood, the system stays in this heightened state after the original threat has passed.
A range of factors appear to feed and maintain it. Ongoing input from an irritable area can keep the system primed. So can stress, poor sleep, and low mood, each of which lowers the threshold at which the nervous system reads sensation as threat. Beliefs play a part too, because expecting movement to be dangerous is itself a signal the brain weighs. Fear and avoidance are a particularly important driver, which is the subject of our guide to the fear-avoidance cycle. This is why settling a sensitised system usually involves more than treating the tissues, and why sleep and stress matter more than people expect (our guide to sleep and pain covers one side of this).
Can central sensitisation be reversed?
Yes. A nervous system that has become sensitised can become desensitised again, because the changes involved are changes in function rather than permanent damage. The dial that was turned up can be turned back down.
The way this happens is by giving the system repeated, believable evidence that it no longer needs to protect so fiercely. Gentle, gradual movement is central to that, because each safe experience is a small message that activity is not dangerous, and over time those messages let the system ease off (our guide to exercise for back and neck pain explains the role of movement). Where fear and avoidance have taken hold, a structured approach called graded exposure is one of the most effective ways to provide that evidence. Tending to sleep, stress, and the beliefs that keep the system braced all add to the effect.
Progress is usually gradual and rarely a straight line. The direction that counts is the trend over weeks and months, as the system slowly recalibrates towards reading ordinary sensations as ordinary again.
When to have it assessed
If your pain has spread, outlasted its expected healing time, or started behaving in the ways described here, an assessment can help identify what is driving it and where to focus. It is also sensible to be aware of the small number of warning signs that mean pain should be checked first, which we set out in when back pain is serious.
Pain that has become oversensitive or spread? I can assess what is driving it and build a plan to help the system settle.
Frequently asked questions
What is central sensitisation in simple terms?
It is when the spinal cord and brain become oversensitive and amplify pain, so that pain is produced more easily and strongly than the situation warrants. Think of it as the nervous system turning up its own volume, so quiet signals are heard as loud ones.
What are the symptoms of central sensitisation?
Common features include pain from things that should not hurt (such as light touch), a larger than expected response to mild pain, pain that spreads beyond the original site or outlasts healing, and sometimes poorer sleep and greater sensitivity to stress, light, or noise.
Is the pain real if it is caused by central sensitisation?
Yes. The pain is produced by a real change in how the nervous system processes signals. You feel it every time, even though it does not reflect ongoing tissue damage.
What is the difference between peripheral and central sensitisation?
Peripheral sensitisation happens in the tissues at an injury site and usually settles as they heal. Central sensitisation happens in the spinal cord and brain, where the amplification can continue and spread even after any injury has recovered.
Can central sensitisation be reversed?
Yes. Because it involves changes in function rather than permanent damage, the nervous system can desensitise over time when it is given repeated evidence of safety through gradual movement and by addressing sleep, stress, and fear.
Does central sensitisation mean the pain is all in my head?
No. It is a measurable change in the nervous system, not imagination. The brain is involved in all pain, sensitised or not, and that does not make the pain any less real.
Sources
Selected references, with confirmed DOI or PubMed links.
- Woolf CJ (2011). Central sensitization: implications for the diagnosis and treatment of pain. Pain, 152(3 Suppl), S2–S15. doi:10.1016/j.pain.2010.09.030
- International Association for the Study of Pain (2017). Terminology: nociplastic pain. iasp-pain.org/resources/terminology/
- Moseley GL, Butler DS (2017). Explain Pain Supercharged. NOI Group.
- Hartvigsen J, et al. (2018). What low back pain is and why we need to pay attention. The Lancet, 391(10137), 2356–2367. doi:10.1016/S0140-6736(18)30480-X
This page is for education and does not replace assessment, diagnosis, or treatment by a qualified health professional. If you notice any warning signs, seek professional help.
