“…Sleep disorders are associated with impairment in immune functioning (1,7), increased mortality and cardiovascular risk (2,5,6). There is an association between sleep quality of HD patients and the following factors; female gender, older age, caffeine consumption, alcohol consumption, tobacco abuse, concurrent comorbidity, recombinant erythropoietin therapies, years receiving dialysis, dialysis shift, depression, physical performance, greater body mass index (BMI) values, dialysis efficiency, anemia, hypoalbuminemia, parathyroid hormone and serum creatinine (8)(9)(10). Deficiency of vitamin D is commonly experienced by patients who undergo dialysis (6,11,12).…”