Daytime sleepiness in stable hemodialysis patients.
BACKGROUND
Patients frequently sleep during hemodialysis (HD), a behavior often attributed to treatment-related fatigue and/or simple boredom. The possibility that this behavior reflects a more pervasive underlying increase in daytime sleepiness has never been systematically examined. Thus, we studied a sample of HD patients on an off-dialysis day to establish the presence or absence of daytime sleepiness independent of effects of treatment, quantify its severity, and identify associated demographic, metabolic, and sleep-related variables.


METHODS
Forty-six stable HD patients underwent polysomnography, followed the next day (a nondialysis day) by the Multiple Sleep Latency Test (MSLT; low score = greater sleepiness), a measure of physiological daytime sleepiness. Subjects also completed the Epworth Sleepiness Scale (ESS; high score = greater sleepiness), a measure of subjective daytime sleepiness.


RESULTS
One third (n = 15) of subjects had MSLT scores suggesting abnormal levels of physiological daytime sleepiness, and six subjects had scores consistent with severe, pathological sleepiness. Thirty percent (n = 14) had significant subjective daytime sleepiness as measured by the ESS. However, MSLT and ESS scores were unrelated. Higher indices of sleep apnea (r = -0.324; P = 0.028) and brief arousals (r = -0.370; P = 0.009) correlated significantly with increased physiological, but not subjective, sleepiness. Longer nocturnal sleep latencies (r = 0.350; P = 0.017) and greater percentage of rapid-eye-movement sleep (r = 0.302; P = 0.042) were associated with decreased physiological sleepiness. Other major demographic, metabolic, and sleep-related variables did not correlate with MSLT scores, and none of the variables examined were related to ESS scores.


CONCLUSIONS
Daytime sleepiness is common in HD patients and may be severe despite the absence of obvious clinical risk factors for the condition. Thus, research designed to identify cost-effective indicators of daytime sleepiness and evaluate the detrimental effects of sleepiness on clinical outcomes in HD patients is warranted.
Parker
Kathy P
KP
Nell Hodgson Woodruff School of Nursing; Department of Neurology, Sleep Disorders Center; and the Renal Division, Emory University, Atlanta, GA, USA. kpark04@emory.edu
Bliwise
Donald L
DL
Bailey
James L
JL
Rye
David B
DB
D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood / Q000453:epidemiology / Q000378:metabolism / Q000628:therapy; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D015995:Prevalence; D006435:Renal Dialysis / Q000009:adverse effects / Q000379:methods; D012720:Severity of Illness Index; D020178:Sleep Disorders, Circadian Rhythm / Q000453:epidemiology*