A new study suggests that having a poor quality of sleep increases one's risk of having heart disease compared to those who are getting the right amount of sleep.

Earlier studies have long associated poor sleep quality with a number of chronic diseases and conditions such as diabetes, cardiovascular disease, obesity and depression. A new study provided new evidence on how sleep affects the heart.

Researchers from the Center for Cohort Studies at Kangbuk Samsun Hospital, Sungkyunkwan University School of Medicine in Seoul, South Korea looked at the data of more than 47,000 young and middle-aged adults. The participants completed a questionnaire asking them of the sleep habits and underwent a series of tests for the heart.

The analysis showed that those who are getting less than five hours per day have a 50 percent higher risk of developing heart disease than those who sleep seven hours a day. Sleeping longer than the recommended hours will not do the trick either, because those who oversleep are increasing their heart disease risk to 70 percent. The researchers predicted the heart disease risk by looking at the amount of calcium in the coronary arteries.

"We also observed a similar pattern when we measured arterial stiffness," said Yoosoo Chang, study co-lead author and associate professor in the Center for Cohort Studies at Kangbuk Samsun Hospital, said in a news release. "Adults with poor sleep quality have stiffer arteries than those who sleep seven hours a day or had good sleep quality. Overall, we saw the lowest levels of vascular disease in adults sleeping seven hours a day and reporting good sleep quality."

The findings of the study emphasize the importance of getting the right amount of sleep on a daily basis as part of one's overall health.

"This adds to the importance of getting a good night's sleep on a regular basis, in addition to regular exercise and a heart-healthy diet, in reducing risk of heart disease," Dr. Mark Urman, a cardiologist with Cedars-Sinai Heart Institute in Los Angeles who is not involved in the study, told HealthDay News.

But how much sleep do we really need? The Sleep Foundation has recommended different guidelines according to age group. For instance, newborns should be able to sleep 14 to 17 hours per day, school children must sleep between nine and 11 hours while adults must sleep at least seven hours but not exceeding nine hours per day.

The study was published in the Sept. 10 issue of the journal Arteriosclerosis, Thrombosis and Vascular Biology.