Chewing your nails is a form of cannibalism - and a sign of low self-esteem, so Clare Paterson decides it's time to stop

Ben, who is 12, will be racing down the football pitch chasing the ball. Seconds later, when he's not directly involved in the action, his hand reaches for his mouth. "Take your hand out of your mouth," I yell from the sidelines, while other parents are shouting, "Oi, ref". When he watches television he starts to nibble. So, too, does his brother, whose fingernails I have never had to cut. Why have I bred a pair of cannibals?

Cannibalism is what it is. At its extreme end, says Dr Pat Frankish, the clinical psychologist, it is a form of self-harm. People eat themselves because they feel they deserve it. At the other end of the spectrum, it is a habit, but it always starts as a way of allaying anxiety. "A child will be anxious, chew their nails, find themselves less anxious and then make the connection between nail chewing and relief." It's what psychologists call "safety-making behaviour". If you can't make the whole world safe, you'll make your world safe.

Psychiatrists must have a field day analysing the hands of American Lee Redmond. She pops up on my children's favourite page of the Guinness World Records. Next to the heaviest twins and the man with the longest tongue sits the woman whose fingernails reach a combined length of 24 feet 7 inches. She displays her hands like an armoury of exotic swords. She hasn't cut them since 1979. She says that if a bomb went off, she's been told she could go into a shelter and live off her fingernails. Her theory on nail-biting is that people do it because they lack a certain mineral in their body. "Rubbish," says Samantha Sweet from Creative Nail Design. "Nail-biting is all in the head."

Apart from it being unattractive, and apart from the nasty nails it creates, biting is unhealthy. I can chew my thumb so much I have to cover it up with plasters to stop the bleeding. You also pick up infections. Children who bite their nails may catch threadworm.

Smokers will say they are going to stop but they just have to finish this last cigarette. Nail-biters will always just need to clean up this last irritating bit of nail that's poking up, and we'll stop after that. The only thing that will make us stop, says Frankish, is if we find something more important or another way of relieving the anxiety. "Keep children's hands busy," she advises. "Then reward that behaviour, so that it's more satisfying than nail-chewing. Don't tell them off for biting." As for Ben on the football pitch, she tells me he's a million miles away, seeking a bit of calm. I've got to stop telling him off and, instead, urge him to keep his mind on the ball.

Adults should occupy their hands, too. Executive desk games, stress-balls or bracelets may do the trick. But they don't work for me. And they didn't work for Frankish's grown-up daughter, who still has the habit. Frankish was a nail-biter herself. "I was shocked out of it," she says. "One day my dad saw my hands and said they were disgusting. I haven't done it since." In fact, that's not quite the end of the story. "At times of real stress, I do still bite the little fingers," she reveals.

For me, bitter nail polish only works for a few hours and instead of feeling disgusted with myself, I feel disgusted at the treatment. I try to keep my hands well moisturised, which helps a little. For habitual biters, Sweet recommends going for a manicure. I didn't go for a pedicure for three years when I had a verruca, and I am loathe to take jagged cuticles and nibbled nails to a parlour for a French polish. I've got to overcome my nervousness, says Sweet. "Having your nails done will affect your personality," she says. "You'll be more animated when you speak. An almond-shaped nail does for the finger what a stiletto heel does for the ankle."

I decide to give it a go. I try not to flinch with shame when I offer my fingers to the nail technician. I've opted, as Sweet advised, for what I think of as falsies. I emerge with immaculate nails twice their normal length. But to keep my hands like this, I would need to return every fortnight and my budget won't stretch to it. I swear I won't nibble and I don't, for several hours. But there's a little bit of jagged skin by the right thumb cuticle, which has got a slight tear in it and I just need to tidy it up with my teeth. That's better.

The only part of the year when my nails come back naturally to their proper shape, and the skin isn't distressed and torn, is when I'm on holiday. After two weeks away, I can tart them up with polish and stop hiding them. "Well, that's telling you the obvious," says Frankish. I'm not sure how much I can change my life. So, I've sent off for a heap of holiday catalogues. It's my only hope.

Finger tips

Keep your nails short. Grow them too quickly and you'll break one and be obliged to nibble the rest down to match.

Go to a properly trained nail technician. The industry isn't regulated, so anyone can set themselves up as a manicurist.

Book yourself regular appointments. Paying out good money may reduce your habit.

Try nail enhancement. You don't have to go for Footballers' Wives-style talons. You need to go back fortnightly or you may substitute picking the enhancement for picking the nail. Clare had a custom-blended manicure with Liza Smith, courtesy of Creative Nail Design (0113-216 3015).

Nails don't breathe, so they don't need a rest from being covered. In fact, enhancements may help retain natural oils.

Men can have manicures too. It's called male grooming.

'Grow Up!' by Clare Paterson will be published by Rodale in the spring