In 1978 my mother came home claiming to be, among other things, a 17th century Catholic priest, a medieval witch and an orphaned Victorian cripple. She'd been (some may say unwisely) dabbling in regression by hypnosis. Eventually, cynicism got the better of her, and she decided it was all in the mind.

I cling to this thought as I approach the home of Evelyn Blandford, the hypnotherapist charged with regressing me to a past life. An appropriately grey-haired Austrian, Blandford begins by taking a brief medical history. Usually, she says, people who come to her would have a particular phobia or emotional difficulty that they wish to "unlock" through hypnosis.

I can't think of anything pressing, so suggest we just see who, if anyone, I once was. She asks me to lie on her couch, and in a slow, slightly sinister voice, tells me, repeatedly, that I'm "deeply relaxed". I do my best. Then she tells me my eyelids are padlocked shut. They feel obediently heavy. She asks me to try and open them. I try, feebly, and can't. But I'm afraid if I try properly they'll pop open, and embarrass us both. After a few more minutes of "relax, relax," I'm starting to feel quite limp, and am no longer afraid I might let out a nervous giggle. Then she asks me to lift out of my body and float up to the clouds. I oblige. After a bit of floating around, she says I should come back down to earth, slowly. I start my descent.

She asks what I'm standing on. My mind goes blank. "Can you see the ground?" "No," I whimper, "not quite." Cobbles? Turf? I'm afraid to commit myself. "Concrete," I say, finally, and randomly. "And where are you?" "A city," I invent. This goes on.

It's 1950, I tell her. I'm a 40-year-old woman and I'm in London. She continues to ask me questions - Where are you? What are you doing? Who are you with? And I produce what I consider to be plausible responses. I feel completely conscious and watch with interest as my story unfolds itself - I'm going to the doctor, I get the results of a fertility test; I'm infertile. I feel suicidal and go to Waterloo bridge - by now I'm having fun, picturing myself despairing in a headscarf clutching my 50s handbag as I tear up the test results and fling them into the Thames.

Sadly, as always, maths proves to be my undoing. She takes me to my deathbed and I say, assertively, that I'm really old. Then I realise I can't be. I was born (in this life, at least) in 1968. I quickly declare that I'm dying of cancer and thus " Feel very old". But we both know I've lost it. She brings me back to the present day with my tail between my legs.

Hypnosis is, Blandford tells me, a useful therapeutic tool. If you have, say, a phobia about knives, the hypnotist will take you back through your childhood looking for repressed memories. If nothing comes up, she may take you to a "past life" to see whether you have, for instance, been knifed to death. I ask, somewhat timidly, if she really believes all this. Her answer is, I think, surprisingly sensible.

Storytelling, she says, has always been an effective way of expressing emotions and issues - she refers to parables in the Bible, or dreams. "If you haven't dealt with a trauma," she says, "then feelings get locked inside." People may produce a "past life" under hypnosis - essentially just a profound state of relaxation - as a way to express a feeling or memory that may be too painful to face consciously. "Whether you believe it was a past life or not doesn't really matter," she points out, "as long as the fear is released, then you can come to terms with it." What this says about my mother's repressed psyche remains mercifully unclear. What it says about me is obvious: I must practise my sums and try to be less cynical.

• Hypnotherapy sessions cost from £25. Evelyn Blandford is based in Cambridge (01223 311807). The National Council for Hypnotherapy: 01509 881477.