Sleep duration and efficiency are associated with plasma amyloid-β in non-demented older people

This study aims to investigate the extent to which sleep duration and efficiency are associated with plasma amyloid-β (Aβ) levels in non-demented older people.

This study is a cross-sectional analysis of 305 non-demented older people. Sleep duration and efficiency were assessed used the Pittsburgh Sleep Quality Index. Levels of plasma Aβ were determined by sandwich enzyme-linked immunosorbent assay technique. Associations between sleep variables and plasma Aβ levels were evaluated with multivariable linear regression analysis.

Compared to those with sleep duration > 7 h, participants with sleep duration < 6 h had a higher plasma Aβ₄₂ level (β = 0.495, 95% CI 0.077~0.913, p = 0.021) and Aβ₄₂/Aβ₄₀ ratio (β = 0.101, 95% CI 0.058~0.144, p < 0.001). Compared to those with sleep efficiency ≥ 85%, participants with lower sleep efficiency (65~74%, <65%) had a higher level of plasma Aβ₄₂ (<65%: β = 0.627, 95% CI 0.147~1.108, p = 0.011) and Aβ₄₂/Aβ₄₀ ratio (65~74%: β = 0.052, 95% CI 0.007~0.097, p = 0.026; <65%: β = 0.117, 95% CI 0.067~0.168, p < 0.001).

These findings indicated that short sleep duration and low sleep efficiency were associated with a high level of Aβ₄₂. A better comprehending of the link between sleep and plasma Aβ levels may lead to effective sleep-based intervention to reduce the risk of Alzheimer's disease.