Working 10 Hour Days Hurts Your Heart

May 11, 2010— -- People who work long hours -- 10 hours a day -- are more likely to have heart-related problems than those who work less, researchers in Britain report in the European Heart Journal.

The researchers followed more than 6,000 civil servants in the U.K. between 1991 and 2004 for an average of 11 years per person, tabulating how much people reported working over 7 hours a day, and their health status.

By the end of the study, people who had worked 10-hour days were 60 percent more likely to have heart problems than people who worked seven-hour days. People who worked 8 or 9 hours a day had no significant increases in heart problems.

In all, the researchers found 396 heart problems in the group, which included death due to heart disease, non-fatal heart attacks and angina.

"I see this as an important new finding from a well-established and trustworthy research group," Dr. Redford Williams, head of behavioral medicine at Duke University in Durham, N.C., told ABCNews.com.

"It's independent of all the usual suspects, including not only blood pressure, cholesterol and overweight, but Type A behavior, not enough sleep and depression," he said.

The researchers tried to statistically control for the effects of smoking, high cholesterol and 21 other risk factors that could influence heart health.

After accounting for the most obvious heart risks, they still found the association between working long hours and heart problems.

But the study only showed an association between working long hours and heart problems.

Researchers say it would take more work to find a cause, and how overtime might hurt a person's heart.