Mysterious pain, such as lower back pain, may originate in the brain rather than the body, according to a study.
Thousands of Britons are believed to suffer from unexplained pains
Scientists from University College London and the University of Pittsburgh carried out tests on eight people.
Some were hypnotised and told they were in pain. Others were subjected to physical pain. Scans showed that both experienced similar brain activity.
The researchers said the findings, published in NeuroImage, suggested that pain can sometimes begin in the brain.
"The fact that hypnosis was able to induce a genuine painful experience suggests that some pain really can begin in our minds," said Dr David Oakley, director of the hypnosis unit at UCL.
A survey published last year suggested as many as one in seven Britons are in constant pain.
In many cases, their condition cannot be explained by doctors, who are unable to identify the cause using conventional tests.
Dr Oakley said the findings showed that patients reporting mysterious pains should not be dismissed by doctors.
"A lot of people have been dismissed as malingers," he said. "People reporting this type of pain are not simply imagining it."
Dr Oakley said the findings suggest that alternative treatments for mysterious or unexplained pain should now be explored.
"If this pain has an origin in the brain it suggests that you can use other therapies, such as hypnosis, to alleviate the pain," he said.
The UK charity Pain Concern said many doctors continue to dismiss patients if they can't find a cause of their pain.
"There are still doctors writing pain off as psychological," a spokeswoman told BBC News Online. "It is a problem. It has a huge impact on patients."