['To determine whether a simple, structured self-report of overall sleep quality is associated with the presence of the metabolic syndrome and its component risk factors.', 'An observational, cross-sectional study comparing global scores on the Pittsburgh Sleep Quality Index with concurrently collected measures of the components of the metabolic syndrome and presence or absence of the syndrome. The metabolic syndrome criterion of the American Heart Association/National Heart, Blood, and Lung Institute was adopted.', 'University laboratory.', 'Two hundred ten volunteers with a mean age of 46 years (57% men) screened for the presence of serious illness and related medications.', 'N/A.', 'All analyses were adjusted for sex and age. Logistic regression showed that poor global sleep-quality scores on the Pittsburgh Sleep Quality Index were related significantly to the presence of the metabolic syndrome-an increase of the global sleep score of 2.6 points (approximately 1 SD) was associated with an odds of having the metabolic syndrome of 1.44 (p = .04, confidence interval = 1.01-2.06). Linear-regression results showed that the Pittsburgh Sleep Quality Index global sleep-quality score was related significantly to waist circumference, body mass index, percentage of body fat, serum levels of insulin and glucose, and estimated insulin resistance.'] Is self-reported sleep quality associated with the metabolic syndrome?