['There is evidence that positive personality characteristics, such as optimism and self-esteem, are important for health. Less is known about possible determinants of positive personality characteristics.', 'To test the relationship of optimism and self-esteem with insomnia symptoms and sleep duration.', 'Sleep parameters, optimism, and self-esteem were assessed by self-report in a community-based sample of 1,805 adults aged between 30 and 84\xa0years in the USA. Moderation of the relation between sleep and positive characteristics by gender and age as well as potential confounding of the association by depressive disorder was tested.', 'Individuals with insomnia symptoms scored lower on optimism and self-esteem largely independent of age and sex, controlling for symptoms of depression and sleep duration. Short sleep duration (<6\xa0h) was related to lower optimism and self-esteem when compared to individuals sleeping 7-8\xa0h, controlling depressive symptoms. Long sleep duration (>9\xa0h) was also related to low optimism and self-esteem independent of age and sex.'] Are optimism and self-esteem related to sleep . Results from a large community-based sample?