Prolonged sleep duration and later wake times predicted worsening cognitive performance, and these effects were strengthened by greater AD pathology.
Longer sleep duration was cross-sectionally associated with worse cognitive/functional performance as measured by CDR-SB.
Later wake time was cross-sectionally associated with worse CDR-SB scores.
Prolonged sleep duration was longitudinally associated with faster cognitive decline.
AD pathology biomarkers moderated the relationship between sleep quality and cognitive decline.
The study enrolled participants from the 1Florida Alzheimer's Disease Research Center and used multiple AD biomarker modalities.
This research suggests that sleeping too long and waking up later in the day are associated with worse cognitive functioning in older adults, and that these relationships become stronger when Alzheimer's disease-related brain changes are already present. The study followed 326 older adults and found that those who slept longer not only performed worse on tests of thinking and daily functioning at a single point in time, but also declined faster over the follow-up period. Importantly, those who had biological signs of Alzheimer's disease — such as amyloid plaques detected by brain scans, elevated tau protein in the blood, or smaller hippocampal (memory-related brain) volumes — showed the strongest links between prolonged sleep and cognitive worsening. This research suggests that excessive sleep duration may be a meaningful warning sign of cognitive decline in older adults, particularly for those who already have underlying Alzheimer's-related brain changes. Rather than longer sleep being protective, in this population it appears to signal or accompany greater vulnerability. The findings highlight the potential value of monitoring sleep patterns alongside established Alzheimer's biomarkers when assessing risk for cognitive decline. The study is notable for using multiple types of Alzheimer's biomarkers — brain imaging for amyloid, blood-based tau, and brain structure measurements — to show that sleep's relationship with cognition is not uniform but depends heavily on the underlying biology of the brain. This points toward a more personalized understanding of how sleep and brain health interact in aging populations.
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Upload Your LabsShihadeh L, Rosselli M, Conniff J, Asken B, Goytizolo A, Barker W, et al.. (2026). Associations among sleep quality, cognitive decline, and Alzheimer's disease pathology in older adults: A longitudinal study.. Alzheimer's & dementia : the journal of the Alzheimer's Association. https://doi.org/10.1002/alz.71470