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To the Editor: In their cohort study assessing the relationship between sleep duration and incident coronary artery calcification, Mr King and colleagues¹ reported an association between longer sleep duration and reduced incidence of coronary artery calcification. The proportion of individuals who developed coronary calcification was markedly greater among participants with actigraphy measurements indicating sleep duration of less than 4 hours per night (measured for 6 nights for each participant).

For many persons, it is difficult to maintain sleep duration of less than 4 hours per night without ingestion of stimulants such as caffeine. Heavy use of caffeine among these participants may have confounded the study results. The relationship between consumption of coffee (the primary source of caffeine in the United States) and coronary risk is controversial. Some studies suggest a U-shaped or J-shaped association between coffee consumption and coronary artery disease.²

Those achieving less than 4 hours of sleep per . . . [Full Text of this Article]

Piyagarnt Vichayavilas, MS, RD
Department of Clinical Nutrition
Children's Hospital of Denver
Denver, Colorado

Caleb Kelly, MS, RD
caleb.kelly@ucdenver.edu
University of Colorado
Denver

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