Purpose: This study was conducted to identify the factors contributing to sleep disorders in patients on hemodialysis. Methods: A descriptive correlational study design was used. The participants were 135 patients on hemodialysis in hemodialysis clinics. Data were collected from March to May 2007 using structured questionnaires and hematologic sample. Stepwise multiple regression was used to identify factors influencing sleep disorders among the demographic-clinical factors, depression and fatigue. Results: About 69% of the patients had a sleep disorders. There were significant differences in sleep disorders according to marital status, caregiver, religion, economic level, insurance, erythropoietin, somnifacient, and antihypertensive agents. But there were no differences according to age, gender, dialysis period, or antidepressants. Their sleep disorders had significant correlations with depression, and fatigue, and a significant negative correlation with Protein, Albumin, Phosphate and BUN. But there were no correlations with hematocrit, hemoglobin, creatinine, sodium, potassium, or calcium. Depression and fatigue were factors influencing sleep disorders. They accounted for 43.8% of the variance in sleep disorders in these patients. Conclusion: Findings provide an understanding of sleep disorders and the factors that are an influence in patients on hemodialysis. To promote sleep in these patients, nursing interventions to manage depression and fatigue are needed.