**10. Restless leg syndrome and periodic limb movement disorder**

Restless leg syndrome (RLS) is a disorder characterized by sensation that usually occurs prior to sleep onset and causes an almost irresistible urge to move the legs, resulting in delayed sleep onset and disrupted sleep (35). RLS may be idiopathic or secondary to other conditions such as pregnancy, rheumatoid arthritis or uremia. Almost 80% of patients with RLS also have periodic limb movement disorder (PLMD), a condition characterized by episodic limb movements associated with nocturnal awakening and disrupted sleep.

RLS has been reported in 14-23% in patient on CHD and 20-57% in CKD patients (21, 36). The prevalence of PLMD is greater than 50% in CHD and CAPD(see glossary) population (1, 2, 35-38). RLS has also been reported to be 4.5% in transplanted patients. The prevalence of RLS is significantly lower in transplant patients than in patients on maintenance dialysis. Declining renal function is associated with increasing prevalence of RLS.

RLS and PMLD may be equally important as sleep apnea in patients with CKD. RLS severity score has been correlated to self perceived sleep problems, nocturnal awakening,

Sleep Disorders Associated with Chronic Kidney Disease 393

Fig. 5. RLS, Insomnia and quality of life in patients on maintenance dialysis.

several small studies (50, 51).

**14. Excessive day time sleepiness** 

(tricylcic antidepressants, Serotonin reuptake inhibitors, dopamine antagonists). Medical therapy includes L-Dopa and dopamine agonists such as pramipexole and ropirinole (64). These medications are favored over benzodiazepines. Gabapentin can also be used as alternative. The frequency of PLMD is not affected by switching from CHD to NHD (28). Kidney transplantation has been associated with an improvement in both RLS and PLMD in

Excessive day time sleepiness (EDS) has been described in dialysis patients. Seventy-seven percent of patients on CAPD reported taking day time naps and 51% reported falling asleep unintentionally (46). The **Multiple Sleep Latency Test** (MSLT) is a sleep disorder diagnostic tool. It is used to measure the time elapsed from the start of a daytime nap period to the first signs of sleep, called **sleep latency**. The test is based on the idea that the sleepier people are, the faster they will fall asleep. The test consists of four or five 20-minute nap opportunities that are scheduled about two hours apart. The test is often performed after an overnight sleep study. During the test, data such as the patient's, EEG, muscle activity, and eye movements are monitored and recorded. The entire test normally takes about 7 hours.In one study, 44 HD patients were studied. Potential subjects with other major chronic conditions or those with medications known to have CNS effects were excluded from the study. In addition, to exclude those with obvious causes of EDS, subjects with a history suggestive of SAS, RLS and PLMD were also excluded. All subjects underwent polysomnography along with MSLT. One third of patients of the subjects had MSLT scores consistent with abnormal sleepiness (mean sleep latency <8min). High AHI was significantly associated with lower MSLT score, but explained only 10% of the variance in MSLT score, suggesting that

delayed sleep onset latency, decreased total sleep time, increased use of sleep medications and self reported nocturnal leg movements (36). Polysomnographic studies of dialysis patients with RLS and or PLMD showed increase in sleep latency, Stage 1 and Stage 2 sleep, and decreased total sleep time and efficiency (38-41).
