The most convincing evidence comes from Sweden. A study by Stockholm University based on the country's 1990 census tracked 25- to 65-year-old adults who died in the ensuing six years and found that each and every step up the educational ladder conferred added longevity. For example, among men who were 64 years old in 1990, about 14 per cent of those with the bare minimum of education had died by 1996. But just six per cent of men with Ph.Ds had died.

What was most intriguing was the difference between men with doctorates and the next step down - men who were slightly less schooled, but nonetheless were professionals, such as lawyers and engineers. The Ph.Ds were surely no richer - but they had a 33 per cent lower mortality rate.

The experts came away from these numbers with this conclusion: more education gives you more control over your life. And more control means less stress. So get your anxious arse off the couch and back to night school.