British scientists have found those working more than 11 hours per day increase their risk of heart disease by 67 percent. Considering heart disease is one of the leading causes of death, a two-thirds increase is very significant. This should be a wake-up call for all those workaholics thinking hard work can't kill you. With that said, scientists were not positive of whether it was the long work hours specifically or the things that working long hours could be associated with (poor diets, lack of exercise, increased depression, etc.) that negatively affected heart health. At this point, for those who are stuck working longer hours, it is recommended to minimize other potential risk factors by getting adequate exercise, adhering to a healthy diet, ensuring they receive adequate rest and sleep as well as effectively dealing with any bouts of depression.
Source: Ann Intern Med April 5, 2011 154:457-463.