Here's an interesting paragraph, pertinent to the discussion of Alzheimer:
"As we learned ..., sleep quality - especially that of deep NREM sleep - deteriorates as we age. This is linked to a decline in memory. However, if you assess a patient with Alzheimer's disease, the disruption of sleep is far more exaggerated. More telling, perhaps, is the fact that sleep disturbance precedes the onset of Alzheimer's disease by several years, suggesting that it may be an early-warning sign of the condition, or even a contributor to it.
Following diagnosis, the magnitude of sleep disruption will then progress in unison with the symptom severity of the Alzheimer's patient, further suggesting a link between the two. Making matters worse, over 60% of patients with Alzheimer's disease have at least one clinical sleep disorder. Insomnia is especially common, as caregivers of a loved one with Alzheimer's disease will know all too well."
The author goes on to discuss the studies his team did in testing the hypothesis of amyloid buildup in the brain (particularly in the frontal lobe, which regulates your sleep) would impact the quality of sleep, and reduce NREM sleep - which is crucial for memory formation and retention.
So even if the amyloid hypothesis doesn't explain the onset of Alzheimer, there's enough evidence to claim that amyloid plaques may be associated with the loss of deep sleep, and damage your memory.
Now the most interesting part is where the author claims the opposite: that lack of sleep is correlated with amyloid buildups, as it disrupts the function of glymphatic system within the brain.