['To examine the association between total sleep duration and the prevalence of metabolic syndrome (MetSyn) in older Chinese.', 'Cross-sectional analysis of baseline data from the Guangzhou Biobank Cohort Study (GBCS) was performed. Participants (n = 29,333) were aged ≥50 years. Risk of MetSyn and its components were identified for self-reported total sleep duration.', 'Participants reporting long (≥9 h) and short (<6 h) total sleep duration had increased odds ratio (OR) of 1.18 (95% CI 1.07-1.30) and 1.14 (1.05-1.24) for the presence of MetSyn, respectively. The relationship remained in long sleepers (OR 1.21 [1.10-1.34]) but diminished in short sleepers (0.97 [0.88-1.06]) after full adjustment.'] Is self-reported long total sleep duration associated with metabolic syndrome : the Guangzhou Biobank Cohort Study?