Those who regularly work long hours may not only be increasing their paycheck, but they may also be significantly increasing their risk of developing heart disease, the world's biggest killer.
Researchers in England said that a long-term study shows that working more than 11 hours per day increased the risk of heart disease by 67 percent, compared to working a standard 7 to 8 hours a day. They say that these findings on working hours could help doctors figure out a patient's risk of developing heart disease, but note that it is not yet clear whether long working hours themselves contribute to heart disease risk, or whether they act as a "marker" of other factors that could harm heart health, such as depression, a lack of exercise, or unhealthy eating habits.
Stephen Holgate, chair of the population and systems medical board at the UK's Medical Research Council, which partly funded the study, said: "This study might make us think twice about the old adage 'hard work won't kill you'."
The study followed 7,100 British workers for 11 years, and was published in the Annals of Internal Medicine journal.
Mika Kivimaki from University College London, who led the research, said that "working long days is associated with a remarkable increase in risk of heart disease" and that the study may be a "wake-up call for people who overwork themselves."