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Lack of sleep in early middle age tied to coronary artery calcification

Reuters Health • The Doctor's Channel Daily Newscast

NEW YORK (Reuters Health) – Objectively measured sleep duration is inversely associated with incident coronary artery calcification in middle-aged adults, independent of traditional risk factors, according to prospective study findings reported in the December 24/31 issue of the Journal of the American Medical Association.

Recent research has tied sleep duration to established risk factors for coronary artery calcification, such as glucose regulation, blood pressure, and body mass index, study director Dr. Diane S. Lauderdale and her team point out. In their current work, they looked for evidence of a direct association between sleep and the incidence of calcification during 5 years’ follow-up.

Their analysis included 495 healthy participants in the Coronary Artery Risk Development in Young Adults (CARDIA) study. Sleep duration was determined by wrist actigraphy at baseline in 2000-2001, when subjects were 35 to 47 years of age. Electron beam computed tomography was used to measure coronary artery calcification at baseline and again in 2005-2006.

Results showed that longer measured sleep was associated with lower incidence of calcification. According to a JAMA statement, the incidence ranged from 6% among subjects who slept more than 7 hours/night, to 11% among those who slept between 5 and 7 hours nightly, and 27% of those who sleep less than 5 hours.

After adjusting for demographics and cardiovascular risk factors, actigraphy-measured sleep per hour was associated with an odds ratio of 0.66 per hour (p = 0.01) for incident coronary calcification.

“The modeled effect of 1 additional hour of sleep on the odds of incident calcification was equal to the modeled effect of a 16.5 mm Hg decrease in systolic blood pressure,” Dr. Lauderdale’s group points out.

“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,” Dr. Lauderdale remarked.

JAMA 2008;300:2859-2866.