['Sleep problems and substance use are strongly linked. Sleep problems play a role in the etiology of substance use, but also may be a result of it. After detoxification, sleep problems may worsen leading to relapse. Nowadays, most substance dependence treatment programs aim at recovery rather than total abstinence, and in that view health-related quality of life (HRQL) is a relevant construct. This article describes the association between self-perceived sleep problems and HRQL in a naturalistic population of polydrug-using inpatients.', 'At the start of treatment, 388 polydrug-using inpatients completed questionnaires concerning their sleep quality and HRQL. Three categories were established based on reported sleep problems: patients without sleep problems (21.6%), those with clinically relevant sleep problems (34.5%), and patients with sleep disorders (43.8%).', 'Mean grades for quality of sleep were M\u2009=\u20097.3 (sd 1.7), M\u2009=\u20096.6 (sd 1.7) and M\u2009=\u20095.3 (sd 1.9) for the three categories, respectively. In addition, patients in the disorder category perceived a lower HRQL than those in the other categories. In the explanation of HRQL, both sleep problems and sleep disorders added significantly to the model when controlling for baseline characteristics.'] Are sleep disturbances associated with reduced health-related quality of life in patients with substance use disorders?