Slow blood vessel movements controlled by norepinephrine help clear brain waste during sleep

Tightly synchronized oscillations in norepinephrine, cerebral blood volume, and cerebrospinal fluid are strong predictors of glymphatic clearance during NREM sleep.

• NREM sleep is associated with reduced processing of external information and activated restorative processes in the brain.
• Optogenetic stimulation of the locus coeruleus resulted in anti-correlated changes in blood vessel motion and cerebrospinal fluid signals.
• Enhanced arterial oscillations were shown to increase the inflow of cerebrospinal fluid, suggesting a pumping action driven by blood vessel movement.
• The sleep aid zolpidem was found to suppress norepinephrine oscillations and glymphatic flow.
• Norepinephrine-driven vascular dynamics play a critical role in the brain's clearance processes during sleep.

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