PEOPLE WHO work three or more hours overtime a day have a 60 per cent greater chance of having a heart attack or experiencing signs of coronary heart disease than those who do not, new research suggests.
Using data from the long-running Whitehall II study of 10,000 civil servants in London, British and Finnish researchers found the significant association between long hours and coronary heart disease was independent of a range of traditional risks like smoking, being overweight or having high cholesterol.
The study, published yesterday, tracked office staff working hours from 1991 until 2004. The analysis looks at the results from 6,014 civil servants aged between 39 and 61.
Dr Marianna Virtanen, an epidemiologist at the Finnish Institute of Occupational Health and University College London, and her colleagues found some 369 subjects had experienced a heart attack or developed angina.
After adjusting for factors such as age, sex and occupational grade, they found three to four hours of overtime – added to a seven-hour working day – was associated with a 60 per cent higher rate of coronary heart disease. The researchers offer a number of possible explanations for their findings, published in the European Heart Journal, including the possibility that working overtime is associated with having a type-A personality (tense, competitive and time-conscious) and not having enough time to unwind before going to sleep. They caution against generalising their findings to blue-collar workers or employees in the private sector.
However, in an editorial commenting on the research, Dr Gordon McInnes, professor of clinical pharmacology at the University of Glasgow, says the findings have implications for cardiovascular risk assessment in the wider population.
“These data from a large occupational cohort reinforce the notion that work stress attributable to overtime is associated, apparently independently, with an increased risk of coronary heart disease.”