BEING an MP leads to higher levels of physical and emotional stress, researchers have found. Well, knock us down with a ballot paper. It is a commonplace that you have got to be pretty strange to want to be an MP, and what are academic researchers for if not for dressing up the commonplace?

What Ashley Weinberg and his colleagues at Manchester University do not ask - and this is an indictment of modern academic research, because it is a far more interesting question - is: do you have to be mad to rule the world?

Now, before mental health charities inundate our letters page, let us make a distinction. We understand that mental illness can be a serious matter, a tragedy for families and individuals. We are aware that much mental disorder is misunderstood, that schizophrenia is nothing to do with a split personality, that terms such as "nutter" and even "care in the community" can cause terrible offence. We know that up to one-fifth of our prison population might be classified as suffering mental health problems, and that mental illness is either symptom or cause of much avoidable suffering at all levels of society.

But it is not a frivolous speculation - at least, not wholly - to wonder whether a certain amount of psychological disturbance is not necessary for the achievement of change in society. Is there not an implication in Mr Weinberg's research that MPs should be doused in tranquillisers and sent off to health farms to relax in white towelling robes? And is this implied search for mental hygiene not, actually, unhealthy?

It is remarkable that, as any historian would tell you, almost all prominent figures in public life are driven characters, overcompensating for some trauma or unhappiness in their early lives. Even the Prime Minister, a balanced young man with untroubled blue eyes, was knocked sideways at the age of 11 by his father's stroke. The even more boring, but equally driven, John Major had that downward lurch to a Brixton garret at a similar age. Margaret Thatcher had that famous reticence about her mother, and became ever more markedly dogmatic in adulthood, eventually prompting Brian Walden's impertinent observation in an interview: "They think you're off your trolley."

Unhappiness is the grit in the oyster. This applies not just to MPs, but to business leaders and great artists. Some of them, at least. Many entrepreneurs had secure childhoods and their start in business handed to them on a plate. But Andy Grove, for example, the boss of Intel, the computer chip company, is a Holocaust survivor and self-confessed paranoid obsessive. He wrote a book which revealed that his hot tip was not to relax for a second, called Only the Paranoid Survive.

And it is a cliche that in art madness and greatness are proximate conditions. Pluck the names at random and images from the simply eccentric to the extremes of human consciousness are conjured forth. Ted Hughes and Sylvia Plath, Vincent van Gogh, Syd Barrett. Of course, for each name it is possible to cite a Sir Paul McCartney or a Joseph Heller. Mr Heller, whose Catch- 22 knows a thing or two about madness, complained recently that he had a happy childhood. Don't you believe it. His father died when he was five, and the books are suffused with a sense of loss, often portraying the father-son relationship as unbearably close and yet uncommunicative.

Of course, madness is not a simple formula for success. It remains true that if someone's childhood is highly dysfunctional, the chances are that they will go off the rails and require the attentions of New Labour's curfew squads and welfare-to-work gangs.

We do not suggest that David Blunkett should amend yesterday's proposals for nursery schooling to ensure that all four-year-olds are unhappy for at least some of the time, or that Jack Straw should institute bad parenting classes.

The requirements of creativity are that the tendency to eccentricity must be bridled by at least an intermittent sense of the possible. Ambition needs to be tempered by restraint. Both are needed, and the most forceful lives are born out of a tension between the two.

This imposes a dilemma on parents: most say they would prefer their children to be happy than to be high achievers. Simone Veil's mother was once asked if she was proud of her daughter, another Holocaust survivor, distinguished minister in French governments and author of the 1975 law to allow abortion. She said she would have much preferred her to be happy.

But we do not employ MPs to be normal, satiated and contented. We employ them to get things done, to overcome the dead-weight of bureaucratic inertia and institutional sclerosis. Let us be grateful that at least some people are unhappy enough to improve the quality of life for the rest.