Association of Sleep Disorders with Nonalcoholic Fatty Liver Disease (NAFLD): A Population-based Study.

BACKGROUND Nonalcoholic fatty liver disease (NAFLD) is a major cause of chronic liver disease. In smaller studies, sleep apnea has been previously associated with NAFLD. The aim of this study was to assess the prevalence and independent associations of sleep disorders in patients with NAFLD using recent population-based data. METHODS Three cycles of the National Health and Nutrition Examination Survey (NHANES) conducted between 2005 and 2010 were used. The diagnosis of NAFLD was established as elevated liver enzymes in the absence of all other causes of chronic liver disease. Sleep disorders were diagnosed using sleep disorder questionnaires completed by NHANES participants, and included self-reported history of sleep apnea, insomnia, and restless leg syndrome. The prevalence of sleep disorders was compared between those with and without NAFLD. RESULTS A total of 10,541 adult NHANES participants with complete demographic, clinical, and laboratory data were included. Of those, 15.0% had NAFLD and 7.2% reported having sleep disorders. Of those with sleep disorders, 64.7% reported history of sleep apnea, 16.0% had history of insomnia, and 4.0% had restless leg syndrome. Individuals with NAFLD were more likely to be male (53.8% vs. 45.7%, P < 0.0001), obese (50.1% vs. 33.4%, P < 0.0001) and had higher prevalence of sleep disorders (9.1% vs. 6.9%, P = 0.0118). In multivariate analysis, having any sleep disorder, sleep apnea and insomnia were all independently associated with NAFLD [OR (95% CI) = 1.40 (1.11-1.76), OR = 1.39 (0.98-1.97), and OR = 2.17 (1.19-3.95); respectively)]. CONCLUSIONS This large population-based data suggests that NAFLD is associated with sleep disorders. Although the exact mechanism is unknown, this association is most likely through metabolic conditions associated with NAFLD.