Sleeping an hour longer daily may lead to a lower chance of the accumulation of calcium plaques in coronary artery 
tracts, predicting possibleheart disease , said a study published in the December 24 issue of Journal of American Medical Association. The researchers report that one additional hour of sleep per night lowered the estimated odds of calcification by 33%.
Christopher Ryan King, B.S. (University of Chicago) and his team started this study in 2001 with 495 individuals( black and white people between the ages 35 and 47) to test if a scientifically measured sleep duration was linked to the development of calcification over a 5 year period.
Coronary artery as a risk factor for atherosclerotic heart disease, also shares many of the other confounding risk factors for heart disease like old age, sex, race, obesity, education, tobacco use, apnea risk,blood pressure, alcoholism and others.
In some recent studies, sleep quantity and quality has been found to be related to several of these risk factors. “However, some of these correlations have only been documented in studies in which sleep is measured by self-report, which may be biased or insufficiently accurate,” write the authors of the study.
Measurements of sleep duration, sleep fragmentation, daytime sleepiness and overall sleep quality were provided by wrist
actigraphy (a tool that monitors rest and activity) and self-reports. The researchers focused the study on the effect that these sleep metrics had on new calcification as detected by computed tomography scans in 2005-2006.
Results indicated that 12.3% (61 participants) developed calcification after 5 years. After controlling of perplexing factors mentioned above. In addition, the magnitude or significance of sleep was not appreciably altered by potential mediators. Sleep metrics other than duration did not appear to be significantly linked to the risk of calcification.
“We have found a robust and novel association between objectively measured sleep duration and 5-year incidence of coronary artery calcification,” write King and colleagues. “This study further demonstrates the utility of a simple objective measure of sleep that can be used at home. Future studies will be needed for crucial extensions to these results. First, these results need confirmation in other cohorts. Second, does sleep moderate the rate at which calcification accumulates? Third, will objective sleep tie to coronary disease event outcomes over the long term? While calcification predicts such outcomes, it is difficult to know how and if the predictors of calcification themselves will determine outcomes, or if their impact will be purely mediated by their effect on calcification. Finally, if this association is born out, interventional studies will be needed to guide clinical advice.”
