Those who spend more than 11 hours at work increase their chance of having a heart attack by two thirds, according to a new study.
Researchers from University College London say the risk is so great that GPs should ask patients what hours they work along with how much they drink or smoke.
The research team looked at more than 7,000 civil servants working in Whitehall over a period of 11 years and established how many hours they worked on average a day, reports Times of India.
Mika Kivimaki, the paper's lead author and a professor of social epidemiology at University College London, said it was not clear whether long working days were causing the increased risk or were simply a marker that could be used to predict risk.
But it is possible, he said, "the chronic experience of stress often associated with working long hours adversely affects metabolic processes," or leads to depression and sleep problems, according to New York Times.