Something else to consider - what if the reason these plaques are unable to be cleaned out in some is the result of a life (decades)-long “deep” sleep deprivation (i.e, still getting sleep but not a good amount of regular, deep sleep where this cleaning process would normally occur), and the reason for this chronic sleep deprivation was some genetic pre-disposition, such as bruxism, which would cause little to no “deep sleep,” or perhaps brought on form of chronic dehydration due to a genetic predisposition for diabetes / sugary drinks / blood sugar imbalance, causing brain fogginess rather than deep sleep during a period of involuntary fasting, or a myriad of other unnoticeable deep- sleep-depriving illnesses?
I am not suggesting I have any answers; only questions and curiosities for the puzzling subject.
You're just considering "involuntary" lack of sleep, when there seems to be a serious epidemic of voluntary sleeplessness as indicated by frequent boasting about how little sleep one can get by on.
Chronic insomnia is still extremely poorly understood, unfortunately, and as other commentators have mentioned in this thread sleep medications are a short term bandage that come with their own harmful side-effects.
As someone who's a chronic insomniac and has been my entire life since I was a baby, I've tried almost everything to sleep with no success. At this point I'm still in my 20s and young, but I worry about having memory and health issues as I age. For now I'm just trying to stay healthy despite it and make a habit of documentation in case my memory does become compromised.
I am not suggesting I have any answers; only questions and curiosities for the puzzling subject.