The scene where William Hurt runs howling like a wolf through the streets of New York has always stuck in my mind.

The movie? Altered States. The reason for his crazed transformation? He spent too long in a float tank.

OK, it was actually a sensory deprivation tank. He was floating in an upright position and completely immersed in fluid. Funny tubes stuck in his nose fed him air. Wasn't this the Seventies prototype of the float tank? No wonder the idea of floating naked in a dark tank of water on my own for an hour gave me the creeps.

I arrive at the south London Natural Health Centre and am every New Age float manager's paranoid nightmare.

'Do people pee in it? is my first question. The tank was not the wartime submarine type coffin I had been expecting, more a small spa pool with attractive lighting, but I still need to know.

'No, people don't, assures Ian Macfarlane, a handsome young PPE (Politics, Philosophy and Economics) graduate who's lost politics and found float tanks instead. He tells me that the water is kept clean by a pump which circulates fresh water through the tank continuously.

'Can I drown? Well, it seems a sensible question, considering people have been known to drown in puddles and bowls of soup. 'No, the salt in the tank keeps you buoyant, he answers. 'It would be impossible to drown in here.

Salt indeed. 300 kilos of Epsom salts had been tipped into the tank. For this reason it was imperative to cover any cuts or minor scrapes with Vaseline provided before immersion.

I stick my fingers in the water, lick them and promptly gag. The water is more liquid fart water than salty sea water. Forget making whale spouts if you get bored.

Left on my own, I undress, push some wax ear plugs into my ears and clamber in. A little inflatable plastic pillow bobs around inside the tank. I slide it under my head. I shut the door and then my eyes.

Soothing jungle music is piped into the darkness. I could have been bobbing about in a warm rock pool in Borneo at night.

The music stops. I am vaguely aware that time is passing. Minutes? Hours? Days? Here in my warm, wet water womb I can no longer tell. Then I pass out.

I awake to water bubbling up near my feet. Remembering that this is the signal that my time is up, I crawl out of the tank. My brain is lobotomised. I am relaxed to the point of stupidity.

When I run into Ian in the hall all I can manage is a meek smile. He directs me down the stairs to Stage Two of the afternoon's de-stressing: the Dancing Dragon aromatherapy massage. I lie face down on the table, a beached seal pup, and Paulina goes to work on my back. Her hands, oiled with various essential oils, do indeed dance like a dragon up and down my back.

Previous massages I'd had were more like being tickled and had made me giggle.

Paulina uses strong 'pressure' on me, which is both hard to stand and easy to take. She asks me a few questions about my general health. By now, I can't speak.

I can shout though - and I do when Paulina attempts to de-tangle the muscles in my shoulders. 'Fibrosis,' she says matter-of-factly.

The knots which had developed over the years of sitting at a keyboard had actually started to grow into my shoulder muscles.

Ten minutes later, Paulina has reduced them to putty. 'Your back is nice and hot now, she says. 'Blood can now flow freely through every muscle.

How I manage to get home by Tube through the afternoon rush hour is a mystery. I just make it to bed.

I go to sleep in one position and wake up in the same position. I haven't felt better in years.

I am now a convert. A floater. It works. And I don't care if I do end up howling like a wolf through the streets.

An aroma-float costs pounds 27 (for an hour's float and half an hour's aromatherapy massage) at The South London Natural Health Centre, 7a Clapham Common South Side SW4 (071-720 8817). Mondays to Fridays 9.30am-9.30pm, Saturdays and Sundays, 9.45am-5pm.

A series of separate introductory floats costs pounds 40 for three.


l Floating is called REST (Restricted Environmental Stimulation Therapy).

l It was invented in the 1950s by Dr John Lilly, a Nasa scientist who stumbled across the idea of water relaxation while working with divers. He claims that an hour's float equals six hours sleep.

l Tanks vary, the most comon being the coffin-type capsule. These can become very humid and are not good for claustro-phobics. Newer models are the size of a double bed.

l They use up to 170 gallons of water and 700lbs of Epsom salts, and are 250mm deep.

l The water is body temperature (35.5 degrees) and the room temperature is 20 degrees).

l There are internal speakers and a light switch you can control.

l Floating produces a deep state of mental and physical relaxation and re-energises the mind and body. You can reach a meditational state of tranquillity which can give clarity of thought for days afterwards.

l Floating benefits everyone, but particularly those in high-stress jobs, athletes and pregnant women.

l For your nearest float centre call: The Floatation Tank Association (0923) 285868. Or Freephone Float (0800) 413416.

(Photograph omitted)