Peripheral circadian oscillators: interesting mechanisms and powerful tools

The lives of plants, animals, and human beings are all regulated by circadian clocks. In mammals, 24-hour rhythms of physiology and behavior are directed by a master clock in the suprachiasmatic nucleus (SCN) of the brain hypothalamus, which in turn entrains "slave" oscillators of similar molecular composition in most cells of the body. These peripheral clocks are interesting not only because they control many aspects of circadian physiology, but also because they are model systems through which we understand how the SCN regulates complex behavior. To this end, peripheral oscillators have been exploited both biochemically to understand the proteins that make up biological clocks, and genetically to decipher the ways in which individual differences in human chronotype might arise

Circadian sleep–wake rhythm disturbances in end-stage renal disease

End-stage renal disease (ESRD) is an increasing health problem worldwide. Given the increasing prevalence of this disease, the high cost of hemodialysis treatment and the burden of hemodialysis on a patient's life, more research on improving the clinical outcomes and the quality of life of hemodialysis-treated patients is warranted. Sleep disturbances are much more prevalent in the dialysis population than in the general population. Several studies investigating the effect and importance of sleep problems on quality of life in dialysis patients revealed that sleep disturbances have a major influence on the vitality and general health of these patients. Sleep disturbances in this patient group are caused both by the pathology of the renal disease and by the dialysis treatment itself. This Review focuses on circadian sleep-wake rhythm disturbances in individuals with ESRD. The possible external and internal influences on sleep-wake rhythmicity in patients with ESRD, such as the effect of dialysis, medications, melatonin and biochemical parameters, are presented. In addition, possible approaches for strengthening the synchronization of the circadian sleep-wake rhythm, such as nocturnal hemodialysis, exogenous melatonin, dialyzate temperature, exogenous erythropoietin, use of bright light and exercise during dialysis treatment, are explored. Further research in this area is warranted, and a greater awareness of sleep problems is needed to improve the quality of life of patients with ESRD