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 h...