Insufficient non-REM sleep intensity in narcolepsy-cataplexy.
OBJECTIVE
To compare electroencephalogram (EEG) dynamics during nocturnal sleep in patients with narcolepsy-cataplexy and healthy controls. Fragmented nocturnal sleep is a prominent feature and contributes to excessive daytime sleepiness in narcolepsy-cataplexy. Only 3 studies have addressed changes in homeostatic sleep regulation as a possible mechanism underlying nocturnal sleep fragmentation in narcolepsy-cataplexy.


METHODS
Baseline sleep of 11 drug-naive patients with narcolepsy-cataplexy (19-37 years) and 11 matched controls (18-41 years) was polysomnographically recorded. The EEG was subjected to spectral analysis.


METHODS
None, baseline condition.


RESULTS
All patients with narcolepsy-cataplexy but no control subjects showed a sleep-onset rapid eye movement (REM) episode. Non-REM (NREM)-REM sleep cycles were longer in patients with narcolepsy-cataplexy than in controls (P = 0.04). Mean slow-wave activity declined in both groups across the first 3 NREM sleep episodes (P<0.001). The rate of decline, however, appeared to be steeper in patients with narcolepsy-cataplexy (time constant: narcolepsy-cataplexy 51.1 +/- 23.8 minutes [mean +/- SEM], 95% confidence interval [CI]: 33.4-108.8 minutes) than in controls (169.4 +/- 81.5 minutes, 95% CI: 110.9-357.6 minutes) as concluded from nonoverlapping 95% confidence interval of the time constants. The steeper decline of SWA in narcolepsy-cataplexy compared to controls was related to an impaired build-up of slow-wave activity in the second cycle. Sleep in the second cycle was interrupted in patients with narcolepsy-cataplexy, when compared with controls, by an increased number (P = 0.01) and longer duration (P = 0.01) of short wake episodes.


CONCLUSIONS
Insufficient NREM sleep intensity is associated with nonconsolidated nocturnal sleep in narcolepsy-cataplexy. The inability to consolidate sleep manifests itself when NREM sleep intensity has decayed below a certain level and is reflected in an altered time course of slow-wave activity across NREM sleep episodes.
Khatami
Ramin
R
Department ofNeurology, University Hospital Zürich, Switzerland.
Landolt
Hans-Peter
HP
Achermann
Peter
P
Rétey
Julia V
JV
Werth
Esther
E
Mathis
Johannes
J
Bassetti
Claudio L
CL
D000293:Adolescent; D000328:Adult; D001611:Beta Rhythm; D002385:Cataplexy / Q000175:diagnosis* / Q000503:physiopathology; D002540:Cerebral Cortex / Q000503:physiopathology; D003700:Delta Rhythm; D005260:Female; D006801:Humans; D008297:Male; D009290:Narcolepsy / Q000175:diagnosis* / Q000503:physiopathology; D017286:Polysomnography; D012016:Reference Values; D012892:Sleep Deprivation / Q000175:diagnosis* / Q000503:physiopathology; D012894:Sleep Stages / Q000502:physiology*
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