Background Psoriasis is a chronic inflammatory skin disease which can cause sleep disturbances due to the disease itself or due to its complications. In this study, we aimed to analyze the array of sleep disturbances caused by psoriasis and to evaluate the interaction between the quality of sleep and the duration and severity of psoriasis. Methods Study subjects included 60 patients with plaque psoriasis and 60 sex- and age-matched controls. The Psoriasis Area and Severity Index (PASI) was used to evaluate severity of disease. Body mass index (BMI), medication usage, and duration of disease were recorded. All subjects completed the Epworth Sleepiness Scale (EES), Pittsburgh Sleep Quality Index (PSQI), insomnia severity index (ISI), Berlin-sleep apnea questionnaire, and questions based on criteria of the International Restless Legs Syndrome Study Group indicating the presence of restless legs syndrome (RLS). Results There were statistically significant and clinically relevant differences between the patients and controls regarding day-time sleepiness (ESS 5.3 vs 4.1, p = 0.037), sleep quality (PSQI 14.4 vs 4.9, p < 0.001), insomnia (ISI 19.7 vs 14.4, p < 0.001), sleep apnea (high risk 30% vs 7%, p = 0.01), and RLS (high risk 32% vs 0%, p < 0.001). Conclusions Patients with psoriasis experience poor sleep quality and are at markedly increased risk for insomnia, obstructive sleep apnea, and restless legs syndrome. These findings suggest the importance of evaluating patients with psoriasis for conditions that affect sleep. The study results further suggest that simple screening tools may be useful for this task.