While sleep disorders are common in Parkinson’s disease and other basal ganglia disorders, information on sleep disturbances in dystonia is limited to generalized forms or Segawa disease. Although many patients with idiopathic cervical dystonia (CD) and blepharospasm (BL) report poor sleep, there are no data on frequency or interactions with well known symptoms like depression and pain. Standardized interviews and assessment instruments, clinical examinations, and self rating forms were applied in 221 patients with CD and BL, and in 93 neurologically healthy controls. Impaired sleep quality was found in 44% of CD patients, 46% of BL patients, and 20% of controls. In dystonia, it was associated with symptoms of depression (frequency of 26%; p < 0.001) and restless legs syndrome (RLS) (frequency of 19%; p < 0.01). Bruxism (in CD; p < 0.05), and female sex (in BL; p < 0.001) were identified as further risk factors, but not severity of dystonic symptoms. Excessive daytime sleepiness was rare in CD and BL (6%). With a frequency of 45%, impairment of sleep quality is common in focal dystonia and associated with symptoms of depression, bruxism, and RLS. Results in CD and BL patients are similar, pointing to an intrinsic mechanism of sleep disturbances rather than a direct effect of dystonic muscle activity. Further studies on sleep in focal dystonia, including polysomnographic recordings, are warranted.