SLEEP AND THE EPILEPSIES

To review the numerous works concerning sleep and epilepsy, this revie w considers the effects of sleep, firstly on seizures and secondly on paroxysmal interictal EEG activity (PA), in the different types of epi lepsy according to the International League against Epilepsy classific ation. Apart from the exceptions of the definite nocturnal preponderan ce of seizures in idiopathic rolandic epilepsy and of the mostly noctu rnal occurrence of seizures in some types of familial or sporadic fron tal-lobe epilepsy, assessing a seizure according to the time of clay i t occurs is of no diagnostic or predictive value. In generalised idiop athic epilepsy, as in partial symptomatic or cryptogenic epilepsy, onl y about 20% of the patients had a sleep increase in PA. This percentag e is higher (75%) in idiopathic partial epilepsy. Stereoelectroencepha lography demonstrates a relative stability of spiking within the focus across the states of vigilance and an increase in transmitted dischar ges during stages 3 and 4. In the Landau and Kleffner syndrome, as in the syndromes of continuous spike-waves during sleep, there is a huge, unexplained increase in PA during sleep. The neuropsychological conse quences of this PA have some relationship with their localisation and the patient's age at the time of occurrence. Sleep PA has also been re ported in several groups of non-epileptic subjects. As regards the eff ect of epilepsy on sleep, sleep may be lighter and abnormally disconti nuous in the absence of seizures, particularly in temporal-lobe epilep sy.