A population-based questionnaire study of 1,818 Australian adults investigated associations of sleep quality with psychological distress and comorbid physical health disorders. The Kessler Psychological Distress Scale and the Behavioral Risk Factor Surveillance System assessed psychological distress and physical health. The Pittsburgh Sleep Quality Index assessed sleep quality. Participants with physical illness or psychological distress had increased odds for reporting poor sleep quality, compared to those with no illness (odds ratios [ORs] D 2.22, for both; 95% confidence intervals [CIs] D 1.53–3.23 and 3.54–10.36, respectively), but those with comorbid illness had markedly higher odds for poor sleep quality (OR D 11.99, 95% CI D 7.90–18.20). Adults with comorbid psychological distress and physical health disorders are at substantially increased risk of poor sleep quality.