The Link of Self-Reported Insomnia Symptoms and Sleep Duration with Metabolic Syndrome: A Chinese Population-Based Study

Study Objectives: The aims of this study are to investigate the relationships of metabolic syndrome (MetS) with insomnia symptoms and sleep duration in a Chinese adult population. Methods: Data from a nationwide epidemiological survey conducted on residents from randomly selected districts in Taiwan in 2007 were used for this cross-sectional population-based study. A total of 4,197 participants were included in this study. Insomnia symptoms, including difficulty initiating sleep (DIS), difficulty maintaining sleep (DMS), early morning awakening (EMA), were assessed using the Insomnia Self-Assessment Inventory questionnaire. Subjects were divided into 3 groups based upon their reported sleep duration (<7, 7-8, and >= 9 h per night). Odds ratios (ORs) and 95% confidence intervals (CIs) derived from multivariable logistic regression were used to evaluate the study aims. Results: The endorsement of DIS and DMS were cross-sectionally associated with the MetS after adjustment for sleep duration (OR [95% CI] was 1.24 [1.01-1.51] and 1.28 [1.02-1.61], respectively). In addition, short sleep duration was significantly associated with the prevalence of MetS independent of insomnia symptoms (OR [95% CI] was 1.54 [1.05-2.47]). However, there was no significant combined effect of insomnia symptoms and sleep duration on the prevalence of MetS. Conclusions: The current investigation shows that short sleep duration and insomnia symptoms, specifically DIS and DMS, were significant correlates of MetS. These findings should be replicated in prospective studies using both sleep duration and sleep quality measures.