Sleep and Epilepsy

Nancy Foldvary-Schaefer, DO; Madeleine Grigg-Damberger, MD

Disclosures

Semin Neurol. 2009;29(4):419-428. 

In This Article

Effects of Sleep Deprivation on Epilepsy

The effect of sleep deprivation on epilepsy has been the subject of much investigation.[23,24] In this review, total sleep deprivation is defined as at least 24 hours of sleep loss; shorter periods of sleep loss are considered partial sleep deprivation (PSD).

Effects of Sleep Deprivation on Seizures

Sleep deprivation has long been recognized as a seizure precipitant, reported by up to one-third of patients with epilepsy, more often in those with awakening epilepsy.[4,25,26] Among 71 patients with partial epilepsy, the odds of a seizure the next day decreased for each hour of sleep the prior night.[25] In another study, night sleep duration was correlated with seizure frequency in 14 patients with temporal lobe epilepsy who maintained sleep and seizure diaries for 2 years.[26] The probability of a seizure was significantly higher after a night of sleep deprivation (at least 1.5 hours less than usual) compared with normal sleep. These findings suggest that modest amounts of sleep loss can precipitate seizures.

Effects of Sleep Deprivation on Interictal Epileptiform Discharges in EEG

In the first systematic study, sleep-deprived EEGs were performed after 26 to 28 hours of wakefulness in 89 subjects with a history of at least one seizure and a normal routine EEG, 34 patients with convulsive epilepsy and interictal epileptiform discharges on routine EEG, and 20 subjects with neurologic disorders other than seizures.[27] Epileptiform abnormalities were recorded in 34%, 56%, and 0% of subjects, respectively. Later, the effect of total sleep deprivation on the EEGs of patients with different types of epilepsies was compared.[24] For most seizure types, spontaneous sleep and sleep-deprived recordings produced similar activation rates. Seizures were more likely to be activated by sleep or sleep deprivation in patients with idiopathic generalized epilepsy than partial epilepsy.

Whether the interictal epileptiform discharges activation produced by total sleep deprivation is due to sleep itself (greater amounts of sleep recorded, sampling effects) or because total sleep deprivation exerts an independent activating effect has been the subject of intense debate. Some have argued that total sleep deprivation does not offer greater activation than sleep alone; others believe total sleep deprivation activates interictal epileptiform discharges independent of sleep induction. Rowan et al found a significantly greater interictal epileptiform discharges yield following total sleep deprivation compared with routine wake and drug-induced sleep EEGs; interictal epileptiform discharges were recorded in 28% of their subjects only following total sleep deprivation, and total sleep deprivation activated a new epileptic focus in 7% of cases.[28] As the yield of recording interictal epileptiform discharges due to repeated recordings was estimated to be in the range of 14 to 19%, the authors concluded their findings were unlikely to be due to sampling effects. The most recent prospective study of 721 subjects who had a second EEG (routine, drug-induced sleep, or total sleep deprivation) after an inconclusive initial EEG found a significantly greater percentage containing interictal epileptiform discharges after total sleep deprivation as compared with a second routine record (22.6% vs. 9.5%).[29] Comparative studies largely confirm that total sleep deprivation activates interictal epileptiform discharges in 23% to 93% of patients with definite or suspected seizures.[30] Whether PSD is a comparable activator remains to be proven.

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