Insufficient sleep duration and quality are associated with various adverse health outcomes. Whereas sleep disorders have been studied in a few skin conditions, data in a more comprehensive dermatology population are lacking. We sought to describe the prevalence, causes, and consequences of sleep disorders in dermatology patients. In this cross-sectional, single-center study, dermatology patients completed a questionnaire addressing skin-related and non–skin-related health, sleep behavior, causes, and consequences of sleep disorders. According to the Regensburg Insomnia Scale, 27.92% of the 634 participants had insomnia (177 of 634 patients). Of these 177 patients, 115 (64.97%) were subjectively sleep disturbed, with skin-related causes accounting for 55.65% (64 of 115 patients), non–skin-related accounting for 33.04% (38 of 115 patients), and combined accounting for 11.30% (13 of 115 patients). Itch was the leading cause of skin-related sleep disorders (64.49%, 50 of 77 patients), followed by skin-related pain (55.84%, 43 of 77 patients) and skin-related fearful thoughts (54.55%, 42 of 77 patients). Sleep disorders reduced daytime performance in 68.70% (79 of 115 patients) and sleep quality of relatives in 20.87% (24 of 115 patients). The prevalence of insomnia among different diagnostic categories ranged from 20.31% to 50.00%. The most common strategy to improve sleep was taking sleep medication (57.39%, 66 of 115 patients).We conclude that sleep disorders are highly prevalent in dermatology patients, often leading to reduced daytime performance, impaired sleep among the patients’ relatives, and increased use of substances.