Changes in the instantaneous heart rate (HR) belong to the vegetative symptoms well-known to accompany epileptic seizures (1,2). Their incidence, extent, and even direction depend on the type of seizures: whereas tonic-clonic seizures in almost all cases show an increase in HR, only 26% of absences are accompanied by a significant change (3), more often demonstrating a decrement (20%) than an increase (6%). In contrast, for complex partial seizures (CPS), increases have been reported in approximately 75% and decreases in only 5% (4-6). Apart from this seizure-type dependency, some authors investigated whether the parameter HRalteration may be useful in differentiating between organic (epileptic) and psychogenic attacks. It was found that psychogenic fits (during the waking state) showed longer-lasting rise phases compared to temporal CPS '(7) and that the amount of increase correlates with the extent of the epileptogenic area involved (8). The present study also was to apply HR as an additional indicator in differential diagnosis potentially confirming the epileptic origin of the attacks. The main point of interest, however, is how to distinguish events occurring during sleep. Here, voluntary (or conscious) psychogenic behavior can be largely ruled out as long as sleep is uninterrupted [to be proven by EEG registration (9)]. Thus, epileptiform EEG patterns during sleep can be more reliable than those registered in the waking state, where the vision may be blurred by (e.g., rhythmical) moving