How does insufficient sleep affect health? Tau protein and β-amyloid (Aβ) are causative agents of Alzheimer's disease. During wakefulness, extracellular levels of metabolic byproducts—including Aβ—significantly increase in the brain. During sleep, these byproducts are cleared from extracellular spaces, preventing accumulation in the brain.Therefore, adequate sleep promotes the clearance of metabolic byproducts like dementia-associated proteins, playing a crucial protective role in cognitive function.
Related studies show that after one night of sleep deprivation in healthy adults, tau protein levels increase by over 50%, and β-amyloid levels rise by 30%. This indicates that sleep deprivation accelerates the accumulation of dementia-related proteins. When sleep duration exceeds 7-8 hours, β-amyloid deposition associated with memory impairment is minimal.Sleep duration between 6-7 hours shows a marked increase in β-amyloid deposition. Sleep duration below 6 hours leads to exponential growth in β-amyloid levels.
Excessive sleep similarly causes memory impairment. Analysis of data from 35 distinct studies involving nearly 10,000 individuals reveals that individuals sleeping over 9 hours daily are prone to memory decline.