We normally regard sleep and wake as two distinct opposing brain states, where sleep requires silence of wake-promoting structures, such as the locus coeruleus (LC)-norepinephrine (NE) system. We set out to investigate how cortical NE dynamics and NE-related astrocytic activity relates to LC population activity during sleep states. We show that LC displays regular phasic activity bouts during NREM leading to a slow oscillatory pattern of prefrontal NE levels of which the majority of NE increases does not lead to awakening. NE troughs link to sleep spindles and continued NE decline transitions into REM. Last, we show that prefrontal astrocytes have reduced sensitivity towards NE during sleep. Our results suggest that dynamic changes in the activity of wake-promoting systems during sleep might allow alternating between crucial sleep processes and broadening of sensitivity towards incoming sensory input.
bioRxiv Subject Collection: Neuroscience