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Epilepsy Research and Treatment
Volume 2013 (2013), Article ID 932790, 10 pages
http://dx.doi.org/10.1155/2013/932790
Review Article

Why Are Seizures Rare in Rapid Eye Movement Sleep? Review of the Frequency of Seizures in Different Sleep Stages

1Department of Neurology, Epilepsy Service, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA
2Department of Neurology, Division of Epilepsy, EEG, and Sleep Neurology, Brigham and Women’s-Faulkner Hospital, 1153 Centre Street, Boston, MA 02130, USA

Received 14 March 2013; Accepted 16 May 2013

Academic Editor: M. Maestri

Copyright © 2013 Marcus Ng and Milena Pavlova. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Since the formal characterization of sleep stages, there have been reports that seizures may preferentially occur in certain phases of sleep. Through ascending cholinergic connections from the brainstem, rapid eye movement (REM) sleep is physiologically characterized by low voltage fast activity on the electroencephalogram, REMs, and muscle atonia. Multiple independent studies confirm that, in REM sleep, there is a strikingly low proportion of seizures (~1% or less). We review a total of 42 distinct conventional and intracranial studies in the literature which comprised a net of 1458 patients. Indexed to duration, we found that REM sleep was the most protective stage of sleep against focal seizures, generalized seizures, focal interictal discharges, and two particular epilepsy syndromes. REM sleep had an additional protective effect compared to wakefulness with an average 7.83 times fewer focal seizures, 3.25 times fewer generalized seizures, and 1.11 times fewer focal interictal discharges. In further studies REM sleep has also demonstrated utility in localizing epileptogenic foci with potential translation into postsurgical seizure freedom. Based on emerging connectivity data in sleep, we hypothesize that the influence of REM sleep on seizures is due to a desynchronized EEG pattern which reflects important connectivity differences unique to this sleep stage.