Poor quality of sleep is a frequent problem among patients on dialysis. The aim of this study was to investigate the association of sociodemographic factors with sleep quality in patients on dialysis. The present study was conducted with 402 patients on dialysis using the Athens Insomnia Scale for the assessment of sleep disorders and a questionnaire about demographic characteristics. The results showed that 41% of the participants had difficulty in falling asleep, 40.3% waking up during the night, 35.6% waking up earlier than desired, 33.3% found the duration of sleep insufficient, 31.8% had a diminished sense of well-being during the day, 24.4% had reduced functioning, and 26.4% had daytime sleepiness problems. Overall, 72.1% of patients suffered from insomnia. Participants undergoing hemodialysis had significantly greater percentage of having a problem with awakenings during the night compared to participants under peritoneal dialysis (p = 0.020). Additionally, women had 1.88 times greater probability of suffering from insomnia compared to men (p = 0.019). Thus, sleep hygiene education programs and intradialytic resistance exercises programs along with early diagnosis of sleep disorders and home dialysis can lead to an improvement of sleep quality in dialysis population.