New research has shown that people who do not get sufficient amounts of sleep each night are more likely to develop hardening of their arteries.

Dr Diane Lauderdale, of the University of Chicago, and colleagues studied 495 men and women. Each participant filled out sleep questionnaires, kept a sleep diary, and wore a wrist actigraphy for 6 nights, a watch-like device that uses a motion sensor to determine actual sleep duration. Participants also underwent two CT scans to assess the extent of coronary artery calcification, one at the beginning of the study and the second at the end of the study five years later.

Results showed that calcified, or hardened, arteries, were found in 27% of participants who slept less than five hours a night, compared with 11% in those who slept five to seven hours, and just 6% in those who slept more than seven hours a night. Also, the benefits of a good nights sleep seemed to be greater in women than in men.  

Dr Lauderdale describes the findings as “something of a mystery”. However, the authors have put forward a number of theories. Firstly, that there may be an unidentified factor that both reduces sleep duration and increases calcification. Secondly, that the 24-hour average blood pressure of those who sleep less may be higher (blood pressure is lower whilst sleeping), thus raising the likelihood of calcification. Their third theory is that stress or a stress hormone such as cortisol, which has been linked to decreased sleep and increased calcification, may play a role.

Dr Lauderdale concludes: “Although there are constant temptations to sleep less, there is a growing body of evidence that short sleep may have subtle health consequences. Although this single study does not prove that short sleep leads to coronary artery disease, it is safe to recommend at least six hours of sleep a night."

King CR, Knutosn KL, Rathouz PJ, Sidney S, Liu K, Lauderdale DS. Short Sleep Duration and Incident Coronary Artery Calcification. JAMA. 2008;300(24):2859-2866.