Sleep disorders in chronic kidney disease

Sleep disorders are highly prevalent in chronic kidney disease (CKD) but are often under-recognized. Restless legs syndrome, which is common in CKD owing to issues with dopamine metabolism and is exacerbated by iron deficiency and uraemia, can lead to poor sleep quality and increased daytime fatigue. Insomnia is also prevalent in CKD, particularly in patients requiring dialysis, with increased sleep latency and sleep fragmentation being reported. The cause of insomnia in CKD is multifactorial - poor sleep habits and frequent napping during dialysis, uraemia, medications and mood disorders have all been suggested as potential contributing factors. Sleep apnoea and CKD are also now recognized as having a bi-directional relationship. Sleep apnoea is a risk factor for accelerated progression of CKD, and fluid overload, which is associated with kidney failure, can lead to both obstructive and central sleep apnoea. The presence of obstructive sleep apnoea in CKD can exacerbate the already heightened cardiovascular morbidity and mortality in these patients, as well as leading to daytime fatigue and reduced quality of life. Increased awareness, timely diagnosis and appropriate therapeutic interventions are essential to reduce the negative impact of sleep disorders in patients with kidney disease. In this Review, Owen Lyons discusses the diagnosis, epidemiology and pathophysiology of three sleep disorders that commonly affect patients with chronic kidney disease - restless legs syndrome, insomnia and sleep apnoea - and their impact on patient morbidity and mortality. Sleep disorders, such as sleep apnoea, restless legs syndrome and insomnia, are very common in patients with chronic kidney disease (CKD), and their presence can have a substantial impact on symptom burden (including poor sleep quality, daytime fatigue and sleepiness), morbidity and mortality.Various treatment options for restless legs syndrome in CKD, including cool dialysate, iron supplementation and gabapentin, can be effective in improving sleep quality and reducing daytime fatigue.Evidence to support the use of sedatives or sleeping medications in CKD is lacking, but cognitive behavioural therapy for insomnia can be effective to improve sleep quality and daytime functioning.Sleep apnoea and kidney disease have a bi-directional relationship; obstructive sleep apnoea is associated with an accelerated decline in estimated glomerular filtration rate, whereas hypervolaemia in kidney failure can lead to obstructive and central sleep apnoea.Intensification of kidney replacement therapy or fluid removal by ultrafiltration attenuates the severity of sleep apnoea in patients with kidney failure.