During deep sleep, glial cells shrink by up to 200%, creating space for cerebrospinal fluid to flush out metabolic detritus.

“during early night deep sleep, glial cells shrink by up to 60%. This creates tunnels for cerebrospinal fluid to power wash the brain, clearing neurotoxins including β-amyloid, tau, synuclein, lactate, and oxidized metabolites at 2 to 4x daytime rates.”

“what happens they discovered is that when you go into deep sleep at night this sewage system kicks into high gear and essentially those glial cells which surround the brain cells themselves the neurons proper they shrink in size by up to 200 percent and then all of a sudden it leaves a vast amount of room for cerebrospinal fluid to start perfusing the brain and washing out the detroit the metabolic detritus of wakefulness”

“Deep sleep is when the brain activates the glymphatic system, a self-cleaning process that rids the brain of metabolic byproducts including amyloid-beta aggregates.”

“A new study in healthy young people found that large amounts of cerebrospinal fluid squirt through the brain every 20 sec during deep sleep. Animal studies have shown this clears away cellular debris and other aggregates that build up in the brain.”

“what she found was that it's during deep sleep that these brain cells actually shrink by almost 60% when we sleep. ... And the cleaning solution is what we call cerebrospinal fluid. And through a pulsatile mechanism during sleep, you get a 10% to 20% increase in the bathing of cerebrospinal fluid through the brain, which washes away all of the metabolic byproducts that have been building up. One of those metabolic byproducts is beta amyloid.”