THE NEUROBIOLOGY OF SLEEP IN EXPERIMENTAL -ANIMALS AND IN MAN

Sleep is a long-term regulated physiological stage that cyclically alt ernates with wakefulness. From a polygraphic point of view two main sl eep stages can be classified: the slow wave sleep (SWS) and the rapid eye movement (REM) sleep. Several functions have been proposed for the SWS and REM sleep, but the brain mechanisms responsible of these slee p stages still have to be well documented for supporting the proposed functions. Conversely, sleep can be pharmacologically modified or disr upted by neurological and psychiatric disorders, however, how they aff ect the sleep mechanisms is still not well determined. Thus, our studi es conducted on experimental animals have been devoted to the analysis of sleep mechanisms, and to find out the sleep changes produced by ne urological disorders such as the temporal lobe epilepsy. Also we have carried out pharmacological studies on geathly human subjects, analyzi ng the effect of various hypnotic agents on sleep and the psychomotor performance on the following day of drug administration. We have also studied the sleep organization of patients suffering from a temporal l obe epilepsy accompanied of psychiatric disorders.Our animal studies s how that some regions of the limbic system are phasically activated du ring REM sleep, and limbic system may ease the onset of this sleep sta ge. Our studies also prove that REM sleep produces a significant delay of epileptogenesis, and that epileptic discharges provoke only a circ adian shift of the REM sleep stage. Human sleep studies on healthy vol unteers show that various benzodiazepines reduce the sleep latency, en hance the SWS-2 percentage and occasionally reduce the percentage of R EM sleep. These pharmacological agents also produce enhancement of the reaction time and time estimating in the morning following their admi nistration. Sleep studies on patients with temporal lobe epilepsy and psychiatric disorders strongly suggest that in these patients the slee p organization is not importantly modified. We also observed that in t hese patients the elements triggering the deja vu phenomena occasional ly coincide with the contents of their dreams.