Koch BCP et al. (2008) Effects of nocturnal hemodialysis on melatonin rhythm and sleep-wake behavior: an uncontrolled trial. Am J Kidney Dis [doi:10.1053/j.ajkd.2008.08.006]

Sleep problems are common in patients with end-stage renal disease. Melatonin secretion rhythms, which control normal circadian sleep–wake patterns, are often disrupted in patients treated with conventional daytime hemodialysis. Koch and colleagues investigated whether switching to nocturnal hemodialysis can restore normal melatonin rhythms and sleep–wake parameters.

Data from 13 patients who switched from conventional thrice-weekly 3–4 h sessions of daytime hemodialysis to four 8 h in-center sessions of nocturnal hemodialysis per week (median age 58 years, 8 men) were assessed. At baseline (i.e. on conventional hemodialysis) and after 6 months of nocturnal hemodialysis, participants completed validated sleep questionnaires, underwent polysomnography, and their salivary melatonin concentration was measured.

Patients reported an improvement in sleep quality and daytime functioning after switching to nocturnal hemodialysis. These findings were confirmed by polysomnography, which revealed significant improvements in median sleep efficiency and deep sleep (from 78.1% to 83.0%, and from 15.4% to 21.2%, respectively). Circadian melatonin rhythms, measured in 12 patients, were impaired at baseline, whereas after 6 months of nocturnal hemodialysis the nocturnal melatonin surge was restored in most patients. The authors also noted an improvement in the efficacy of dialysis when patients switched from conventional to nocturnal hemodialysis.

Koch et al. explain that the sleep-related advantages of nocturnal hemodialysis might result from the activation of sleep-inducing mechanisms, such as body cooling, and the resynchronization of sleep–wake patterns with the circadian cycle.