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Thursday, 17 September, 1998, 23:37 GMT 00:37 UK
Heart attack risk from short working week
man post-MI with nurse
Heart attack risk is related to work hours
People who work less than a normal working week are more likely to suffer a heart attack, according to research.

A study published in the British Medical Journal found that, compared to people who work an average of seven to nine hours a day, those who work fewer than seven are three times more likely to suffer a heart attack.

However, the risk is two-and-a-half times greater for those who work more than 11 hours a day.

Genuine link

Researchers in Japan set out to investigate if there was a genuine link between the number of hours someone works and their chances of having a heart attack.

They found that people who work very few or very long hours are at greatest risk of suffering a heart attack.

They also found that the risk increased as the hours piled up.

Spurts of overtime are particularly dangerous. People who work a normal week, but then have days when they work three or more hours overtime are two-and-a-half times more likely to suffer a coronary as someone who works just one hour extra.

The study looked at 195 men who had been admitted to hospital with heart attacks, and compared them to 331 healthy men.

Working hours

On discharge, each patient completed a questionaire giving details of the average number of hours they had worked in the two months before the attack.

office work
Office hours are ideal
They also listed the months in the previous year when they had worked the longest and the shortest hours.

Dr Shigeru Sokejima, of the Toyama Medical and Pharmaceutical University team, led the research.

He said that a healthy lifestyle may deteriorate if people work shorter hours.

Possible explanation

Periods of unemployment were another possible explanation for the finding as it would lower the average number of hours worked over the four months studied by the researchers.

Thety said the reason risk increased with longer hours was possibly due to blood pressure.

An earlier study established that blood pressure is higher at work, and consistently high blood pressure can cause a heart attack.

Sudden changes in the average time worked could increase risk because the body's natural rhythm may not be able to adapt, Dr Sokejima speculated.

He called for further research to find out why time worked affects the risk of heart attack.

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