Daytime Sleepiness in Dialysis Patients May be a Significant Medical
ATLANTA -- Clinicians have long noted that hemodialysis patients sleep
during treatment, a phenomenon that has often been attributed to fatigue.
But during her clinical work as a nurse practitioner, Emory nurse researcher,
Kathy Parker, PhD, RN, FAAN, began to suspect that this problem might
really be excessive daytime sleepiness ≠ the inability to maintain an
alert, awake state.
Dr. Parker conducted a study
designed to establish the presence or absence of daytime sleepiness
in these patients and to identify associated demographic, metabolic,
and sleep-related correlates. The results were recently published in
the February issue of the American Journal of Kidney Diseases.
Dr. Parker and her Emory
colleagues studied a sample of 46 otherwise healthy hemodialysis patients
on a non-dialysis day so they could assess the prevalence and severity
of daytime sleepiness independent of the effects of treatment. Subjects
underwent a laboratory-based polysomnogram to measure nocturnal sleep.
Using conventional criteria, the researchers manually scored the sleep
stages, apneas and hypopneas, periodic leg movements, and brief arousals.
Sleep variables were calculated and included total sleep time, sleep
efficiency, and percentage of total sleep time spent in the stages of
non-Rapid Eye Movement (REM) sleep and REM sleep.
The next day, subjects had
a Multiple Sleep Latency Test (MSLT), a laboratory-based daytime nap
study that measures how quickly an individual falls asleep in a dark,
quiet room (physiologic sleepiness). Subjective sleepiness, an assessment
of an individualís chance of dozing during the day, was measured via
the Epworth Sleepiness Scale.
One-third of the subjects
had MSLT scores that suggested abnormal levels of physiological daytime
sleepiness were present and 13% had scores consistent with severe, pathological
sleepiness. Over 30% exhibited significant subjective daytime sleepiness.
Subjects with greater physiologic sleepiness had greater numbers of
apneas and brief arousals in their sleep at night. No correlation between
physiological and subjective sleepiness was found, suggesting that hemodialysis
patients may physiological be very sleepy but have little insight into
the severity of the problem.
The results indicate that
daytime sleepiness is common in hemodialysis patients and may be severe
despite the absence of obvious clinical risk factors for the condition,"
the researchers wrote. "Thus, research designed to identify cost-effective
indicators of daytime sleepiness and evaluate the detrimental effects
of sleepiness on clinical outcomes in hemodialysis patients is warranted."
The study was funded by the
National Institute of Nursing Research. Dr. Parkerís research team included
colleagues from Emory Universityís Department of Neurology (Sleep Disorders
Center) and the Renal Division.