A new study reveals that people who don't get much sleep are more likely to develop calcium deposits in their coronary arteries, possibly raising their risk for heart disease. The 495 study participants filled out sleep questionnaires and kept a log of their hours in bed. In addition, at night they wore motion-sensing devices around their wrists that estimate the number of hours of actual sleep.

 

At the beginning, none of participants, aged 35 to 47, had evidence of coronary artery calcification. However, five years later, 27 percent of those who were sleeping less than five hours a night on average had developed coronary artery calcification for the first time, while only 6 percent of those who were sleeping seven hours or more developed it. Furthermore, among those who were sleeping between five and seven hours a night, 11 percent had developed coronary artery calcification.

 

After analysing the data, the researchers concluded that one hour more of sleep per night means a 33 percent decrease in the odds of calcification, comparable to the heart benefit gained by lowering one's systolic blood pressure by 17 millimeters of mercury. This study has been published on Tuesday in the Journal of the American Medical Association. The data were drawn from the ongoing Coronary Artery Risk Development in Young Adults study.

 

However, some experts still say that this does not prove a cause-and-effect relationship between the lack of sleep and heart disease, and that's because a third, unrelated factor might exist. Higher education levels are also associated with both a lower risk of heart disease and a tendency to get more sleep.

 

Another hypothesis states that the lack of sleep may lead to increasing blood levels of the stress hormone cortisol, which can raise the risk of coronary artery disease over time. Furthermore, blood pressure dips when people are asleep, so, therefore, sleeping may provide health benefits for those who get more of it.