Well, actually, you won't. Nor will you start clucking like a chicken in front of your friends. In fact, you won't lose control at all. Hypnotherapy isn't a quack fairground entertainment; it's a serious practice that some believe should be available on the National Health Service. Elaine Williams investigates the power of positive suggestion.
The sensation is like emptying your head, apparently, or going from fifth gear into neutral. For David, a senior teacher, who is trying to describe what happens when he is under hypnotherapy, the driving analogy is more than a little appropriate. He has a phobia of motorways.
But hypnotism has done more for him than just enable him to cope with the nation's highways, for the fear was merely the symptom of an underlying problem - work-related stress.
David's problems began when he was made a head of department at the age of 27. "It was at the time when there were lots of changes in the national curriculum, and I was finding it difficult to cope - I was a bit too young," he admits. First of all his driving suffered, then he started to feel increasingly depressed, especially at home and during weekends and holidays.
After a long period of constant medical referrals, eventually a psychotherapist advised him to try hypnotherapy. Suddenly, things at last began to improve. Under hypnosis he found he was able to relax "more than I had for years" and was far more positive about himself.
"It's really about the power of positive suggestion," he says. "I had got to the point where all my thoughts were negative, I was always worrying about something, living in a nightmare. Hypnotherapy allows you to let yourself go."
At first David attended hypnotherapy once a week, and then once a fortnight. Now, four years later, he still visits every six to eight weeks for a "top-up", although he has learned some self-help techniques to help him through stressful periods.
"I am now back to the person I was seven or eight years ago," he says. "I know my limitations stress-wise. I have been able to maintain my career and gain promotion. Five years ago I wouldn't have been able to do this job, I wouldn't have coped."
David's account seems far removed from the showground image many people have of hypnotists, of a man with a pocket watch on a chain, or television's Paul McKenna mesmerising people so they cluck like chickens. Few of us would wish to lose control to that extent, and the entertainment value it provides serves only to discredit hypnotism as a therapeutic tool.
But hypnotherapy is a different beast altogether, and recent years have seen a surge of interest in the practice. Earlier this month, it was reported that Arsenal football club was employing a hypnotherapist to help striker Dennis Bergkamp overcome his fear of flying. Even though the story proved to be a hoax, the newspaper's decision to run the story shows how the therapy is gaining credibility.
Suzanne Chamier, a hypnotherapist in York, claims to have more teachers on her books than people of any other profession. "A lot of it is performance-related," she says, "teachers unable to cope with big classes, or holding assemblies, experiencing panic attacks that kind of thing. But it's also to do with overload, putting in 120 per cent, taking on too many extra-curricular duties, fearing to take time off because of the burden that places on other teachers."
She admits patients are baffled about the way hypnotherapy works. Rather than going into the expected trance, patients are awake and aware of everything being said. But, because they are relaxed, the conscious mind is relaxed. "That's when I start putting in suggestions that go down through the conscious mind, down into the unconscious, and that starts the process of changing patterns of thinking," explains Suzanne Chamier.
Christine Stables, secretary of the National Register of Hypnotherapists and Psycherapists, describes it as a two-way process that leaves the client in full control. At no point should he or she be unaware of what's going on. Hypnotherapists employ relaxation techniques similar to yoga. A client concentrates on breathing and muscle relaxation and blocks out external events and stimuli. He or she is then ready to engage in therapy to help change behaviour, thought or feeling.
"A good analogy would be that being under hypnosis is like being engrossed in a really good film or book," says Ms Stable. "You're aware of what's happening around you - noises in the street, sounds of people moving about the house - but you're not paying any heed. However, if the telephone rings, you will come out of this hypnotic state and answer it."
It is not known whether people under hypnosis enter a special state that is different from ordinary consciousness and sleep, or whether they are merely extending their consciousness. Few would claim to really understand how hypnosis works, but many claim that work it does.
Ian, a former teacher who retired early because of ill health, had suffered from ulcerative colitis for 28 years. A year ago he saw an advertisement in the local paper from a hypnotherapist and took a chance. "I had nothing to lose," he says. "The therapist listened to me for quite a long time and then he hypnotised me. I felt incredibly relaxed."
After only two sessions Ian began to notice a change. "I was walking into town and I suddenly realised I wasn't feeling bad," he says. "After four sessions the benefits really started to show, though the reduction of pain and improvement in the illness was very gradual. My digestive system started to calm down and I started to have control over it."
All in all Ian had nine sessions with the hypnotherapist, during which he also learned self-hypnosis. "I like to help myself," he says."I don't like throwing myself on someone else's mercy, so when I needed to feel less agitated I would go and lie down somewhere comfortable and talk to myself."
Hypnotherapy has enabled Ian to feel well and stay well. Dr Peter Whorwell, a physician in the gastro-enterology department at Withington Hospital, Manchester, runs a hypnotherapy unit of six staff - therapists not medics - as part of his clinical practice. A pioneer in using hypnosis to relieve bowel disorders, Dr Whorwell has used clinical trials to prove that hypnotherapy can improve the quality of life, particularly for those who suffer from bowel abnormalities. "This is a powerful treatment," he says. "Hypnotherapy can put people back to work again. Moreover, there are no side effects - the worst that can happen is nothing."
Dr Whorwell, who manages the only department in the United Kingdom to use hypnotherapy, receives referrals from the UK and abroad. He believes hypnotherapy should be available on the National Health Service and criticises health authorities for being reluctant to pay for it when they are willing to pay for drug remedies. Health professionals, too, he says, tend to ignore it.
While a good hypnotherapist would never promise a cure, practitioners claim it can be effective in dealing with common problems such as a fear of heights and spiders, and claustrophobia; disorders such as arthritis, asthma and irritable bowel syndrome; weight control; improving sports performance; dampening down cravings and addictions such as smoking, and helping with job-related stress.
The problem, says Dr Whorwell, is that the sector is unregulated and its claims are largely anecdotal and have not been proven through clinical trial. That does not mean people shouldn't use it, but it does mean that without the science the medical mainstream remains unconvinced.
* HOW TO FIND A HYPNOTHERAPIST
If you're considering hypnotherapy, it's probably not a good idea to go forthe pin-in-the-Yellow-Pages approach. This is a highly unregulated sector, so