Dissociated wake-like and sleep-like electro-cortical activity during sleep

► Intracerebral EEG recordings revealed local cortical activations during NREM sleep. ► Local activations were paralleled by a deepening of sleep in other cortical regions. ► Wake-like and sleep-like EEG patterns can coexist in different cortical areas. ► Sleep process is not necessarily present simultaneously in the entire brain.