Cancer patients should be offered hypnosis therapy to help reduce their pain, researchers said yesterday after a series of scientific studies.

Tests with patients as young as six found they reported and showed less discomfort when they were hypnotised or learnt how to hypnotise themselves.

The children were undergoing treatments such as lumbar punctures - where a long needle is inserted into the spine - and who suffered continual pain from cancer, said Dr Christina Liossi of the University of Wales in Swansea at the British Association Science Festival in Exeter.

"Hypnosis improves the quality of life for children and adults with cancer," she said. "It may also improve the length of life, though we are not yet sure on that. We need to put it into clinical practice. We now have experimental evidence that hypnosis is an intervention, at least with children who undergo painful treatment procedures."

Her call came after the outcome of a study with 80 children in Greece, who clearly showed less reaction to pain when hypnosis techniques were used. Children who were not hypnotised, but simply engaged in comforting conversation, reported and showed more pain than hypnotised ones.

Although hypnotism is often made available as an alternative therapy, the work by Dr Liossi suggests that it should become part of standard clinical practice. She is now about to start a second full study in Swansea.

Scientists agreed that after years when debate has raged over whether hypnosis has a real basis or is just a pretence, there is now clear data showing that important brain functions change when somebody "goes under" a hypnotist's spell.

"Brain scans show that in hypnosis there's a disconnection by a part of the brain called the anterior cingulate gyrus, which monitors what we are doing in the here and now," said Dr Peter Naish of the Open University.

"In stage hypnosis, the reason why people can do outrageous things that they wouldn't normally do is that that structure, which monitors the emotional consequences of our future behaviour - what if I do this or that - doesn't understand the consequences of following the hypnotist's instructions."

Scientists are less clear how hypnotism works in the easing of pain - although they now feel sure that it does. "Studies in the US show that rather than ignoring pain, hypnotised patients appear to be attending to it, focusing on the pain in order to deal with it," said Dr Naish.