A new study conducted on 495 participants found that the ones who don’t get much sleep are more likely than those who do to develop calcium deposits in their coronary arteries, therefore raising their risk for heart disease.

The participants were asked to fill a sleep questionnaire and keep a track of their sleeping hours. They were also asked to wear a motion-sensing device around their wrists at night. The device estimated the number of hours of actual sleep.

Participants got another coronary artery CT scan at the end of the five-year study. About 12% had developed coronary artery calcification.
At the first scan, none of the volunteers had any calcification in their arteries but five years later 61 of them did. This calcification appeared to be linked with lack of sleep.

Lead researcher Dr Diane Lauderdale, of the University of Chicago, said they had been able to find many explanations for the link between calcification and sleeplessness. But at the same time she also commented that the report does not establish any cause-and-effect relationship between the two.

Lauderdale and her team had reason to be skeptical. While the connection between sleep and heart disease is of growing interest to researchers, earlier studies had been inconclusive, and plagued by biases, including the fact that most of the trials relied on people's self-reported accounts of their sleeping habits.

Calcium deposits can make the coronary arteries less flexible and ultimately lead to heart disease. After adjusting for lots of potential risk factors, such as sex, race, and smoking habits, the researchers found that one more hour of sleep a night decreased the risk of calcification by a third. That's about as much as a 16.5-point reduction in blood pressure, the researchers said.