Sleep and epilepsy.

One of the main advantages of long-term recording of epileptics is the possibility to monitor these patients during natural sleep. In this chapter, we first describe the reciprocal influence of sleep and epilepsy. On the one hand, sleep and circadian fluctuation of the state of vigilance have a marked influence on the occurrence of generalized and partial seizures as well as on the frequency, morphology and distribution of interictal epileptic discharges. On the other hand, a wide range of sleep disturbances has been documented in epileptics and there is some evidence that sleep disturbance and epilepsy may aggravate and perpetuate one another. Long-term EEG monitoring during sleep is of major importance when investigating epileptics with nocturnal attacks to determine whether these nocturnal episodes represent an ictal manifestation or an independent non-epileptic sleep disorder. In special forms of epilepsy, sleep recording is not only useful but necessary for the diagnosis. Various activation procedures are carried out on patients in whom there is diagnostic uncertainty regarding the presence or the type of epilepsy. Some of these procedures employ sleep: namely sedated sleep, sleep after sleep deprivation and all-night sleep recording. The diagnostic value and the indications of these activation studies are reviewed.