When Dr David Spiegel's wife Helen gave birth to the couple's two children, she dealt with the pain by imagining she was floating on Lake Tahoe. Her first labour lasted for 12 hours, but she required no pain relief medication and gave birth to a strapping 10lb baby.

"Women go through fairly substantial pain when they give birth, but it's a wonderful happy experience and you know that the pain doesn't signal lasting damage to your body," says Dr Spiegel. "It's a matter of just learning to focus your attention on other things."

All very well for him to say, you might think, but when it comes to matters of mind over body, Dr Spiegel, a former President of the Society for Clinical and Experimental Hypnosis who is based at Stanford University medical school, knows what he is talking about.

While hypnosis still suffers from its unfortunate association with gimmicky stage shows, more is being discovered about its power and that of the human brain. "Our brain is this very complex computer that tells us what to pay attention to and what to ignore," says Spiegel, who is also director of the Centre on Stress and Health at the Department of Psychiatry at Stanford. "If we were aware at any one time of 1% of everything, we would be totally immobilised."

Spiegel believes focused concentration can offer a real alternative to pain relief drugs. "The brain is really good at filtering in and out information: you have to pay attention to pain in order for it to hurt. Brain imaging studies show that during hypnosis you don't just feel the same pain but report that it's okay, you actually reduce your perception of pain. We have more control over our bodies than we give ourselves credit for."

Dr Spiegel is interested in using hypnosis in a clinical setting and estimates that two thirds of the population can be hypnotised, often in one 45-minute session. "Studies show that during stressful medical procedures, ranging from invasive radiological imaging studies and needle biopsies through to actual lumpectomies, you can teach patients to do self-hypnosis to release their pain and anxieties, decrease the amount of pain meds they use and shorten procedure time." Hypnosis can also be useful for the treatment of chronic illness. "We teach patients in support groups to learn to filter out the pain, focus on something else, imagine the part of their body that hurts is warmer or cooler. We get a 50% reduction in pain over a year or so."

A former president of the American College of Psychiatrists, Spiegel has been in Scotland assessing the Maggie's cancer care centres as part of an external review. Much of his own research has been used to improve the experience of cancer patients. As he walks round the Glasgow centre he talks about how social support is a major stress buffer. "We are social creatures. We think of ourselves as splendid individuals but we are more like ants than eagles. We don't survive without social connection and yet what happens to people when they get cancer is that they get socially isolated. If you stress people alone you get a much higher psychophysiological stress response that if you gave them the same stressor but when there are other people with them."

The previous day Spiegel was speaking with patients at the Maggie's centre in Edinburgh who told him that the centre had made them feel part of a community for the first time since their diagnosis. One of the defining features of the centres is that they allow people to speak to others in a similar situation.

"We are finding that it is very damaging to try to suppress negative feelings," says Spiegel. "If people want to put on a happy face, we call it the prison of positive thinking', it's a bad thing. As a psychiatrist, if somebody has a bad case of cancer and isn't sometimes sad, angry and fearful, I worry about them because they ought to be. We're finding that you actually get reductions in stress physiology when you're more open and expressive about all of the feelings that you have."

Again, he cites research showing that discussion groups change people's tendency to express emotion and make them feel more confident about managing their emotion, both of which serve to reduce anxiety and long-standing depression.

At Stanford, Spiegel and his team have spent decades exploring the links between social environment, mind and body, links which he describes as strong but not simple. "How much stress you experience, how you handle that stress and the social support you have certainly affects your quality of life. It may even have an effect on the way that the disease progresses. It's not the case that you can wish away cancer in your head or just put on a happy face and the cancer will go away. We have these two extremes that the public thinks: that either doctors say take your medication and that's it, or patients think; If I fix my head I can fix my body'. Neither of those is true but the mind and the body do interact."

Indeed, modern life and its associated stresses are leaving us more prone to illness than our ancestors. "We drive around in fancy four-wheeled wheelchairs so that we keep our bodies from exercising. We are isolated from other people so that you don't bump into people when you are going home, you honk your horn at them if they cut you up. We've erected lights that have completely disrupted our circadian rhythms (our natural 24-hour cycle) so we sleep far less than we should. We have evidence in our laboratory that disrupted circadian patterns predict an earlier progression of breast cancer, for example.

"A lot of the things we do - bad diets, lack of exercise, lack of social encounters and disrupted sleep cycles - are bad for our physiology and put us at higher risk through things like obesity and smoking."

In addition to physical factors that can make us vulnerable to illness, Spiegel believes that stress, trauma and depression can make people more susceptible to illnesses such as cancer. "The literature is complicated but there are large-scale studies showing that objective stressors like losing a spouse, or a job, are associated with a higher incidence of breast cancer. Some 19 of 24 recent studies show that being depressed is associated with more rapid progression of cancer.

"Maggie's centres are offering support for the long-term effects and the stress is the one thing which is going to be with you the most because you are going to be going back every year, having tests and possibly developing multiple cancers," says Spiegel.

"Some of the comfort offered by hypnosis or other forms of support becomes incredibly important as this evolves."

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