BACKGROUND: The authors investigated the relationship between self-reported sleep characteristics and brachial artery flow-mediated dilation (FMD) in a community-based population. Previous studies document that sleep apnea may be related to endothelial dysfunction but disagree whether subjective reports of sleep may also reflect such associations. METHODS: In 684 subjects (32% male) aged between 37 and 60 years enrolled in the Emory-Georgia Tech Predictive Health Institute study, the authors measured reported sleep characteristics using the Epworth Sleepiness Scale and the Pittsburgh Sleep Quality Index (PSQI) along with cardiovascular risk factors. Endothelial function was assessed using brachial artery FMD. Multivariate analysis of covariance was used to adjust for various cardiovascular risk factors including age, race, gender, smoking, hypertension, diabetes and body mass index. RESULTS: Lower brachial artery FMD values were correlated with higher Epworth Sleepiness Scale scores (P = 0.0275), even after adjustment for risk factors (P = 0.03). Total PSQI score was unrelated to brachial artery FMD. However, lower sleep quality (PSQI component 1) was associated with lower brachial artery FMD (multivariate P = 0.038), and participants who coughed or snored during sleep also had lower brachial artery FMD (6.24% ± 3.42%) compared with those who did not (6.92% ± 4.30%) (P = 0.056). This difference remained significant after adjustment for risk factors (P = 0.03). CONCLUSIONS: In a community-based population, our analysis indicates a significant association between sleepiness and snoring assessed by questionnaires and endothelial function. Simple subjective reports about individuals' sleep may be highly revealing indicators of endothelial function impairment and thus important indicators of cardiovascular disease risk.