Glymphatic

Recent research has shown that sleep allows for the clearing of toxic substances from the brain. It does this through the glymphatic system, which is the brain's equivalent of the lymphatic system.

Hence, an increase of BWC^([brain water content]) can only occur though an increased flow of water from the intravascular space into the brain parenchyma by an increase in glymphatic influx or by a reduced glymphatic efflux.

The glymphatic system is most active during sleep and is largely disengaged during waking hours.