INTRODUCTION Sleep duration and quality have been associated with obesity. Sleep disturbance has been reported to be associated with stress and depression among non-obese populations, but these relationships have not been previously examined in the obese population. The objective of the current study was to examine the complex associations among sleep disturbance, quality of life, anxiety, and depression in a patient sample with severe obesity. METHODS Two hundred seventy consecutively recruited patients with a mean body mass index (BMI) of 47.0 kg/m² were studied. The correlation coefficient, multiple linear regressions, and structural equation modeling (SEM) analysis were used to evaluate the association between the Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS), Impact of Weight on Quality of Life-Lite (IWQOL-Lite) and Hospital Anxiety and Depression Scale (HADS). RESULTS The mean (standard deviation; SD) PSQI score was 8.59 (5.11), and mean ESS score was 8.84 (5.79). After controlling for potential confounders, poor sleep quality and excessive daytime sleepiness were found to be significantly associated of all the components of IWQOL-Lite; physical function (β = -0.32, β = -0.27; P < 0.01), self-esteem (β = -0.23, β = -0.30; P < 0.05), sexual-life (β = -0.30, β = -0.35; P < 0.05), public distress (β = -0.39, β = -0.39; P < 0.01), and work (β = -0.26, β = -0.48; P < 0.01). We also found that the PSQI global score had a positive significant association with anxiety (β = 0.29; P = 0.01) and depression (β = 0.31; P = 0.01) components of HADS. CONCLUSION Poor sleep quality was strongly associated with mood disturbance and poor quality of life among extremely obese patients. Future interventions are needed to address sleep disturbance to prevent further development of psychological co-morbidity and potentially worsening of obesity among these individuals.