Can pessimists learn to be optimists? If so, they could lengthen their lives, an American study shows. Research on nearly 100,000 women found that pessimists on the whole had higher blood pressure and cholesterol; but even with those risks, optimists fared better than their cynical sisters.

Optimistic women had a 9 per cent lower risk of developing heart disease and a 14 per cent lower risk of dying from any cause after more than eight years of follow-up. In comparison, pessimistic women who harboured hostile thoughts about others or were generally mistrusting of others were 16 per cent more likely to die over the same time scale.

Why? Optimists may be better at coping with adversity; they might take better care of themselves when ill. Those in study exercised more and were leaner. Hostile emotions release certain chemicals in the body which may increase the risk of heart disease, and they may go hand in hand with habits like smoking and poor diet. Beyond that, the researchers are not prepared to say why attitude makes a difference.

But it’s a difference that matters even more to men. A Dutch study published a few years ago found that those classed as optimists in 1985 were 55 per cent less likely to die of heart disease or stroke by 2000 when taking major factors such as smoking and family history into account.

To come back to our original question -- the research all natural born pessimists are waiting for is that which shows what can turn them into positive, hopeful people. Telling them just to improve their diet and smoke less seems like taking away the few pleasures they have.