Sleeping longer may signal early Alzheimer's-related brain changes

Regularly sleeping long hours each night is associated with higher levels of an Alzheimer's-related protein in the blood, even accounting for other health factors, suggests a new study from UT Health San Antonio, the academic health center of The University of Texas at San Antonio.Modeling across a sample of 2,410 study participants found a link between sleep duration and phosphorylated tau 181, or p-tau181, a modified form of tau protein that is a hallmark of Alzheimer's disease, and is now detectable in blood.Regular sleep durations beginning at eight-and-a-half to nine hours per night were associated with higher p-tau181 levels, increasing most sharply beyond 10 hours, suggesting that long sleep might reflect early neurodegenerative processes.

A lot of people worry about whether their sleep habits are affecting their brain health. Because this is a snapshot in time rather than a long-term study, we cannot say that long sleep causes Alzheimer's, but the findings suggest it may be worth monitoring, and that more sleep is not always better for brain health."

Vanessa M. Young, PhD, MS, postdoctoral research fellow, Glenn Biggs Institute for Alzheimer's and Neurodegenerative Diseases, UT Health San Antonio

Young, also a trainee at the Sam and Ann Barshop Institute for Longevity and Aging Studies at UT Health San Antonio under a National Institutes of Health Institutional National Research Service Award (T32) grant, is first and corresponding author of the study, titled, "Non-linear associations between sleep duration and plasma p-tau181 in the Framingham Heart Study," published May 19 in Alzheimer's & Dementia, the Journal of the Alzheimer's Association.She is a graduate of the Translational Science PhD Program in the Graduate School of Biomedical Sciences at UT Health San Antonio, and at the Biggs Institute is under the mentorship of founding director Sudha Seshadri, MD.The study's participants from the Framingham Heart Study – an ongoing community-based cohort study of residents in Framingham, Massachusetts, under the direction of the National Heart, Lung, and Blood Institute of the National Institutes of Health – had an average age of 70, plus/minus 8.45 years, with 55.2% female.The effort follows a similar one in 2025 in which sleeping nine hours or more per night was associated with worse cognitive performance, particularly for those with depression. The latest study, with several of the same researchers, went further and accounted for multiple health factors and examined blood-based biomarkers implicated with Alzheimer's disease and neurodegeneration in relation to participants' self-reported sleep duration.