WORKERS who regularly clock up 10 or 11-hour days could be up to 60pc more likely to suffer heart disease and death, researchers have warned.
A study of more than 6,000 people found that overtime is bad for the heart, with those working longer hours feeling more stressed and having less time to unwind.
The study was carried out on a group of British civil servants and published online in the European Heart Journal.
Men and women aged between 39 and 61 took part in the study, and were followed for an average of 11 years.
Their risk of suffering a heart attack or angina, or developing heart disease that led to them dying, was assessed over the course of the study. Overall, there were 369 cases where people suffered heart disease that caused death, had a heart attack or developed angina.
Researchers found that even when factors such as age and whether people were overweight or smoked were taken into account, overtime was linked to a 60pc increased risk of heart disease or dying compared with people who did not do overtime.
The increased risk was linked to working between three and four hours extra a day on top of a normal seven-hour day.
Marianna Virtanen, an epidemiologist at the Finnish Institute of Occupational Health in Helsinki and University College London, led the study.
She said: "The association between long hours and coronary heart disease was independent of a range of risk factors that we measured at the start of the study, such as smoking, being overweight or having high cholesterol.
"Our findings suggest a link between working long hours and increased coronary heart disease (CHD) risk, but more research is needed before we can be confident that overtime work would cause CHD."
The researchers said there could be a number of explanations for the possible link.
These may include "hidden" high blood pressure that is not always picked up, stress, anxiety or depression, and being a 'Type A' personality who is highly driven, aggressive or irritable.
People who do not sleep for enough hours or have "insufficient time" for winding down after work before bed may also see their risk increased.
"Employees who work overtime may also be likely to work while ill -- that is, be reluctant to be absent from work despite illness," the experts said.