Sleep Disorders in Chronic Kidney Disease Patients

Sleep disorders are prevalent in patients with chronic kidney disease (CKD) in particular those with end stage renal disease (ESRD). It has been reported that 80% of ESRD patients receiving dialysis report sleep complaints, with daytime sleepiness to be the most common reported symptom. The reason for increased rates of sleep related issues and disorders in this population is likely multifactorial. Although it is commonly accepted that patients with CKD experience poor sleep quality, not much is known about the physiological mechanisms underlying this phenomenon. Patients with CKD often exhibit sympatho-vagal imbalance due to baroreceptor reflex function impairment in which there is hyperactivity of the sympathetic nervous system and decreased vagal tone. In healthy individuals, sleep is accompanied by a decrease in sympathetic activity and an increase in vagal tone that leads to a nocturnal dipping of blood pressure. However, patients who have sleep disorders resulting in hypoxemia and sleep fragmentation have been shown to have increased sympathetic nervous system stimulation and decreased parasympathetic activity, which results in a reduced fall in nocturnal blood pressure. In patients with ESRD, the identification, diagnosis and treatment of sleep disorders is complicated by the overlapping presentation with CKD and other commonly comorbid conditions. One approach to conceptualizing this relationship is to consider sleep disorders as secondary or end product of multiple concurrent and interactive processes. Such processes include psychological disorders (depression, anxiety), lifestyle factors (coffee/nicotine use, sleep hygiene), treatment-related factors (timing of dialysis, daytime napping, production of cytokines, thermoregulatory changes, dialysis disequilibrium syndrome, disruptions in circadian rhythm, medication side effects) as well as intrinsic, ESRD-specific factors (anemia/obstructive sleep apnea (OSA) and other comorbidities, uremia, overall all health and quality of life, alterations in neurotransmitter production). A poor sleep profile is associated with increased risk of CKD development. Therefore, sleep duration and quality should be considered when developing strategies to improve sleep and thus prevent CKD. Poor sleep quality, which is commonly found in pre-dialysis CKD patients, is an independent factor associated with cardiovascular damage in CKD patients. Both short and long sleep durations are significantly associated with CKD and proteinuria. Some findings suggest curvilinear dose-response associations of sleep duration with CKD and proteinuria. Optimizing sleep quality and duration to \>6 h/night improved BP control and was associated with a significant delta change in systolic blood pressure (SBP) within 3 months of follow-up. Physicians should obtain a sleep history in patients with CKD who present with resistant hypertension. Poor sleep quality is prevalent in patients on maintenance haemodialysis, and is associated with increased daytime sleepiness. Depression further compounds this relationship, and is significantly associated with increased daytime sleepiness and restless leg syndrome.