describe the brain's "Glymphatic System". What does this system do? How does it do it? What fluids (blood, CSF,
ISF) and compartments (cerebral arteries & veins, perivascular space, subarachnoid space, parenchyma etc) are involved? Do these fluids "mix", or are they kept separate during operation of the glymphatic system? What allows the system to operate at night, during deep sleep, and not at other times? When the glymphatic system is dysfunctional/impaired, or otherwise not allowed to function normally (for example, because of chronic deep-sleep deprivation), what kinds of brain diseases may arise and/or be exacerbated? Why?