Relationship of epileptic seizures to sleep stage and sleep depth.
OBJECTIVE
Interictal epileptiform discharges (IEDs) are facilitated by NREM stages 3 and 4 sleep and as sleep is deepening. To determine whether sleep influences seizures in a similar way to IEDs, we examined seizure rates in various stages of sleep in epilepsy patients undergoing overnight video-EEG-polysomnography (VPSG).


METHODS
Cross-sectional study.


METHODS
Neurology Department. PATIENTS, MEASUREMENTS, AND INTERVENTIONS: We reviewed VPSGs from our Sleep and Epilepsy Laboratories to identify patients with recorded seizures during sleep. A total of 55 patients having 117 seizures were identified.


RESULTS
Ninety-five percent of seizures occurred in NREM sleep (61% in stage 2, 20% in stage 1, 14% in stages 3 and 4 combined), and 5% in REM sleep. Adjusting for time spent in each stage of sleep, patients had 0.34 seizures per hour in stage 1, 0.38 seizures per hour in stage 2, 0.29 seizures/hr in stage 3 and 4 combined, and 0.09 seizures per hour in REM sleep. Seizures/hour was higher in NREM sleep (0.35 for NREM and 0.09 for REM; p=0.0001). For single seizures occurring in 1 night, seizure rate was significantly higher in NREM stages 1 and 2 as compared to NREM stages 3 and 4 sleep. A significant increase in log delta power, an automated measure of sleep depth, was observed in the 10 minutes prior to seizures.


CONCLUSIONS
Both seizures and IEDs are facilitated by NREM sleep. While deeper stages of NREM sleep activate IEDs, lighter stages of NREM sleep promote seizures, at least for single seizures occurring in 1 night.
Minecan
Daniela
D
Department of Neurology, University of Michigan Medical School, USA. dminecan@umich.edu
Natarajan
Alamelu
A
Marzec
Mary
M
Malow
Beth
B
D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D003430:Cross-Sectional Studies; D004569:Electroencephalography; D004576:Electromyography; D004585:Electrooculography; D004827:Epilepsy / Q000175:diagnosis / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D012720:Severity of Illness Index; D012894:Sleep Stages / Q000502:physiology*; D012895:Sleep, REM / Q000502:physiology; D013997:Time Factors