 An additional aim of this study is to examine the impact of obstructive sleep apnea OSA on the pathogenesis of nonalcoholic fatty liver disease NAFLD, both common comorbidities of obesity. Recent evidence indicates a potential link between OSA and severity of NASH and fibrosis, but the mechanisms of OSA- associated hypoxia on liver disease progression in NAFLD is unclear. This study offers the unique opportunity to analyze this association, as the study population will undergo routine evaluation for OSA, as part as the preoperative work-up prior to bariatric surgery. 