No cognitive processing in the unconscious, anesthetic-like, state of sleep.
The Journal of comparative neurology February 1, 2021 Robert P Vertes, Stephanie B Linley 9 citations
The brain during non-REM sleep is in an unconscious state akin to general anesthesia, making meaningful cognitive processing impossible. Waking experiences are never faithfully reproduced in sleep but appear in distorted forms. Both non-REM sleep and general anesthesia share features such as sensory blockade, immobility, amnesia, and loss of awareness, characterized by delta oscillations across the cortex, reduced neural activity especially in frontal and parietal regions, and disrupted functional connectivity in thalamocortical and corticocortical networks. Disrupting the cortex, particularly the orbitofrontal cortex, impairs higher-order cognitive functions. The profound cortical deactivation in non-REM sleep would negate any possibility of memory processing or consolidation.