Orfxin A level and its relation to sleep disorder among chronic renal failure patients on maintenance hemodialysis

Dialysis patients frequently complain of insomnia, excessive daytime sleepiness, restless leg syndrome and sleep apnea. Uremia is considered as a major factor for developing sleep disorders in chronic renal failure patients. The aim of this work was to study the types of sleep disorders found in uremic patients on maintenance hemodialysis and to try to find the possible role of orexin A in the development of these sleep disorders. This study included forty subjects classified into three groups. Group I [n=20], included those patients with chronic renal failure on maintenance hemodialysis. While group II [n=10] included those patients with chronic renal failure in predialysis stage. and compared with 10 age and sex matched control subjects [group III]. All subjects were subjected to full history taking and complete clinical examination and routine laboratory tests. Overnight polysomnographic study in a specialized sleep lab was done for all subjects. Serum orexin A levels were assayed for all subjects by commercial Kit by EIA. Polysomnographic data in uremic patients, compared with control group showed significant rise in sleep onset and arousal index. Also sleep efficiency and deep sleep were significantly reduced in uremic group of patients. Restless leg syndrome was prevalent in uremic patients with significant increase of limb movement index than in control group. There was no significant difference between patients on hemodialysis and predialysis patients in most sleep parameters. Serum orexin A level was significantly higher among uremic patients compared to the control. Serum orexin A level showed significant positive correlation with arousal index and significant negative correlation with sleep efficiency in the two uremic groups. It was concluded that several sleep disorders as insomnia and restless leg syndrome are prevalent among uremic patients. High serum orexin A level may play an important role in the development of these sleep disorders which did not show any improvement with the conventional hemodialysis