BACKGROUND

Patients with end-stage renal disease (ESRD) have a high prevalence of sleep disorders, which are not improved by conventional hemodialysis (CHD). Although sleep disorders are commonly associated with complaints of excessive daytime sleepiness, the severity and pathogenesis of daytime sleepiness has not been evaluated objectively in patients with ESRD. Nocturnal hemodialysis (NHD) is a new technique that provides better clearance of uremic toxins than CHD and, consequently, may improve sleep quality and daytime sleepiness. The authors wished to determine the severity and pathogenesis of daytime sleepiness in patients with ESRD and evaluate the impact of NHD.

METHODS

Sleep quality was monitored by overnight polysomnography, and daytime sleepiness was assessed by the multiple sleep latency test (MSLT). These measurements were performed in 24 patients (15 men and 9 women, 44 +/- 10 years) while on treatment with CHD and were repeated in 15 patients after conversion to NHD.

RESULTS

The majority (54%) of patients on CHD were pathologically sleepy (somnolent group, mean sleep latency <5 minutes), and, in comparison with the remaining patients (alert group, mean sleep latency >5 minutes), their blood urea nitrogen (BUN; 77.9 +/- 9.8 v 60.2 +/- 12.0 mg/dL, P < 0.001; 27.8 +/- 3.5 v 21.5 +/- 4.3 mmol/L; P < 0.001), and periodic limb movement (PLM) index (57 +/- 47 v 6 +/- 10/hr; P = 0.002) were significantly higher. Furthermore, sleep latency was correlated with BUN (R = 0.58, P = 0.008). After conversion to NHD, there was a significant fall in BUN and the severity of sleep apnea, but the overall frequency of PLM and sleep fragmentation remained elevated. Nevertheless, there was a trend for the Somnolent group to become less sleepy on NHD, and this was associated with a modest reduction in the frequency of PLM.

CONCLUSION

Excessive daytime sleepiness occurs in approximately 50% of patients with ESRD. The etiology appears to be related both to uremia and sleep fragmentation associated with PLM.