A new study has found that office workers in England significantly increased their chances of having a heart attack by working more hours than their peers.
The study, conducted by researchers at University College London, found that employees who regularly worked 11-hour days or longer were 67 percent more likely to develop heart disease than those who worked seven- or eight-hour days.
One U.S. expert said many factors could account for the rise in risk among those tied too long to the office.
"Those working long hours may have less time for exercise, healthy eating and physicians visits," said Dr. Gregg C. Fonarow, associate chief of cardiology at UCLA's David Geffen School of Medicine. "They may be exposed to more stress, get less sleep and engage in other behaviors which contribute to cardiovascular risk."
The study, published in the April 5 issue of the Annals of Internal Medicine, followed a low-risk population of almost 7,100 British civil servants from 1991 until 2004, screening out those with signs of heart disease.
About 70 percent of the workers were men, and most (91 percent) were white. Roughly 2.7 percent developed coronary heart disease by the end of the study, the researchers found.
Participants reported how many hours they spent on the job, including work they took home with them. More than half (54 percent) put in between seven and eight hours a day, while 21 percent worked a nine-hour day, and 15 percent spent 10 hours on the job daily, the study found. Slightly more than 10 percent labored 11 hours or more.
Besides bumping up the risk for heart disease by 67 percent compared to people working an eight-hour day, working 11-plus hours a day also put some people into a whole other risk category, the team found.
"Adding working hours to the Framingham risk score improved identification of persons who later developed heart disease," explained study co-author Mika Kivimaki. The Framingham risk score, aimed at gauging heart disease risk, is developed from data that includes age, sex, blood pressure level, cholesterol levels, and whether or not a patient smokes, said Kivimaki, a professor of social epidemiology at University College London.
