A NEW study has revealed that working for more than 40 hours a week may increase one's risk of developing coronary heart disease ,or narrowing of the blood vessels that supplies blood and oxygen to the heart. According to Dr Yul Chul Hong, Senior author of the study , from the Department of preventive Medicine , Seoul National University, the longer hours employees worked , the higher their chances of developing coronary heart disease within ten years, with those working 61 to 70 hours having a 42% increased likelihood of developing the disease , those working 71 to 80 hours having a 63% increased likelihood and those working more than 80 hours having a 94% increased likelihood. The researchers studied 8,350 South Korean adults .They asked them about working hours and their health,performed physical exam and took blood. They