PEOPLE on performance-related pay are working themselves to death, according to a new study.

Researchers detected a strong correlation between the length of time workers spent in jobs where they were paid for performance and incidences of poor health.

Professor Keith Bender and Professor Ioannis Theodossiou, from Aberdeen University's ­Business School and Centre for European Labour Market Research, made the conclusion after analysing survey results of more than 2500 people from across Britain.

The research comes as many firms are maintaining pay freezes, some of which have been in place for a number of years.

Mr Bender said surprisingly little research had been conducted into this area, despite observations about the effect of this type of employment going back as far as the 18th century.

He said: "We can all think of common phrases like 'working yourself to death', but hardly any research exists to quantify this.

"The economist Adam Smith observed workers in the 18th century and noted that if you paid workers by the ton of coal they pulled out of the ground, they were more likely to work themselves so hard that they would 'ruin their constitution'."

Mr Bender added that almost all previous research has focused on specific occupations, but the ­Aberdeen team had wanted to investigate the impact across a wide variety of occupations.

He said the results remained unchanged - workers reported greater odds of ill health the longer they were employed in performance-related contracts, although the types of illness or injury did change.

He said: "One of things we know from economic theory is that performance-related pay makes explicit to workers the value of their time. You have to work to get paid and that makes people very aware of the 'cost of time'.

"Therefore, instead of going and exercising at lunchtime, they are more likely to stay working, or to work late at night having a take-away rather than going home and preparing a healthy meal.

"This is not going to cause illness or injury immediately but there is likely to be a cumulative effect on health if done consistently over time."

It was also noted that people who were paid by performance were more likely to drink heavily than those in other types of contracts such as being paid by the hour or a salary.

The research is to be published in the journal Oxford Economic Papers.