Non-specific pain refers to pain for which there is no recognised physical cause, despite clinical investigation, and which is likely to be stress-induced. Physical pain is a very common symptom of psychological stress. Around 96% of people will experience headache during their lifetime and nearly 90% of these will be stress-induced tension headaches. Similarly, as many as 84% of people will experience back pain during their lifetime and a similar proportion of these cases are likely stress-induced.