A new study warns that people who work for longer hours are at a higher risk of developing heart diseases.

Heart diseases are the leading cause of death in American men and women. The U.S. Centers for Disease Control and Prevention (CDC) suggests that about 600,000 people in the U.S. die due to heart disease, which accounts for 1 in every four deaths. Coronary heart disease (CHD) is the most common type of heart diseases, which kills about 380,000 Americans each year.

Health advocates believe that being overweight, excess intake of alcohol, diabetes, poor diet and physical inactivity are some of the key reasons of developing heart diseases. Researchers suggest that working long hours can also contribute to higher risks of heart diseases.

"Working hours not only affect physical health outcomes, but also lifestyle conditions, such as dietary patterns, exercise, smoking habits, and alcohol consumption," per the researchers. "It is highly probable that cardiovascular diseases are affected by overtime work, because the risk factors of cardiovascular diseases are influenced by working hours."

Many health advocates are in agreement that working over 40 hours in a week can lead to stress, dissatisfaction, bad social life and other health issues. A new research conducted on over 8,300 Koreans aged over 19 years suggests that working over 40 hours a week can also increase the risk of CHD.

The participants of the research revealed information such as general health, working hours and some lifestyle factors, which included diet, physical activity, alcohol intake and smoking habits. The participants were also physically examined for blood pressure, glucose levels, cholesterol levels, and more.

The researchers used the Framingham risk model, an algorithm that calculates the chances of developing CHD over a certain time period (usually 10 years), using information provided by a participant.

Dr. Yun-Chul Hong, senior author of the American Journal of Industrial Medicine study, reveals that the longer a participant worked, the higher was the possibility of developing CHD over 10 years. The researchers point out that if a person works for 61 to 70 hours, the likelihood of CHD increases by 42 percent.

It gets worse if a person works for more hours as the study highlights that working 71 to 80 hours per week increases the risk of the disease to 63 percent and working for over 80 hours each week and even spike the risk of CHD to a whopping 94 percent.

Around 18 percent of Americans are believed to be working for 60 hours or more a week. The excess time worked definitely increases the amount of money an individual takes home but it comes at the cost of higher risks of developing CHD in the future.

The study has been published in the American Journal of Industrial Medicine.