Working long hours can increase a person's risk of developing heart disease, a new study suggests.
People who work 11 or more hours a day have a 67 percent higher risk of coronary heart disease than people who work seven or eight hours a day, the study found.
Coronary heart disease occurs when blood vessels that supply blood and oxygen to the heart are narrowed, and is caused by atherosclerosis, which is the hardening of arteries due to buildup in the arterial wall. It can lead to chest pain, heart attack and death, according to the National Library of Medicine.
The new study will be published April 5 in the journal Annals of Internal Medicine.
To begin the study, British, French and Finnish researchers screened 7,095 civil service workers, ages 39 to 62, who had no signs of coronary heart disease. They were screened initially between 1991 and 1993, and then screened every five years afterward until 2004.
Fifty-four percent of the people worked 7 to 8 hours a day, and 10.4 percent worked 11 or more hours as day.
By the end of the study, 192 people had developed coronary heart disease, the study said.
Researchers found that adding information about the study participants' working hours improved predictions of who would develop coronary heart disease in that 10-year period.
The more hours people worked in a day, the higher their risk of developing coronary heart disease, the results of the study suggested. People who worked 10 hours a day had a 45 percent higher risk of heart disease and those who worked 11 hours a day had a 67 percent higher risk of heart disease than people who worked 7 to 8 hours a day, according to the study.
Therefore, asking patients about their work schedules could give doctors a better idea of patients' heart disease risks, researchers said.
Next, researchers hope to see whether the association holds true across income levels. It also needs to be determined if working long hours is a causal risk factor for coronary heart disease, or if it's just associated with increased heart disease risk.
Past research also suggests a link between working hours and heart disease risk. A 2010 study published in the journal Heart showed that men who did not regularly exercise had an increased risk of dying from ischemic heart disease if they also worked more than 45 hours a week, compared with men who worked less than 40 hours a week.
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