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\u2019s disease, and is now detectable in blood.<\/p>\n
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.<\/p>\n
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Vanessa Young, PhD, MS<\/p>\n
\u201cA lot of people worry about whether their sleep habits are affecting their brain health,\u201d said\u00a0Vanessa M. Young, PhD, MS<\/a>, a postdoctoral research fellow at the\u00a0Glenn Biggs Institute for Alzheimer\u2019s and Neurodegenerative Diseases<\/a>\u00a0at UT Health San Antonio. \u201cBecause this is a snapshot in time rather than a long-term study, we cannot say that long sleep causes Alzheimer\u2019s, but the findings suggest it may be worth monitoring, and that more sleep is not always better for brain health.\u201d<\/p>\n Young, also a trainee at the\u00a0Sam and Ann Barshop Institute for Longevity and Aging Studies<\/a>\u00a0at 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, \u201cNon-linear associations between sleep duration and plasma p-tau181 in the Framingham Heart Study,\u201d published May 19 in\u00a0Alzheimer\u2019s & Dementia, the Journal of the Alzheimer\u2019s Association.<\/p>\n She is a graduate of the\u00a0Translational Science PhD Program<\/a>\u00a0in the\u00a0Graduate School of Biomedical Sciences<\/a>\u00a0at UT Health San Antonio, and at the Biggs Institute is under the mentorship of founding director Sudha Seshadri, MD.<\/p>\n The study\u2019s participants from the Framingham Heart Study \u2013 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 \u2013 had an average age of 70, plus\/minus 8.45 years, with 55.2% female.<\/p>\n The effort follows a\u00a0similar one in 2025<\/a>\u00a0in 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\u2019s disease and neurodegeneration in relation to participants\u2019 self-reported sleep duration.<\/p>\n The long and the short of it<\/p>\n Both short and long sleep duration have been associated with Alzheimer\u2019s disease risk, yet the nature of the \u201cnon-linear\u201d associations between sleep quantity and blood-based biomarkers of the disease and neurodegeneration has been understudied. Non-linear, in this case, means the relationship between sleep and the biomarker is not a straight line, but rather it changes in strength depending on how much someone sleeps.<\/p>\n The study notes that dementia affects 57 million individuals globally, with Alzheimer\u2019s disease accounting for 60% to 70% of cases. Even with recent advances in disease-modifying therapies, Alzheimer\u2019s remains a profound medical and societal challenge.<\/p>\n Thus, identifying modifiable risk factors that could enable diagnosis, prevention or delay of disease onset is a critical research priority. Sleep is a promising modifiable risk factor linked to the disease, but existing evidence has remained limited and inconclusive.<\/p>\n In clinical studies, Alzheimer\u2019s biomarkers are measured as surrogates of the disease\u2019s pathology in the brain, and the recent expansion in easily obtained plasma biomarkers has opened the way for more thorough examination of the relationship between sleep and Alzheimer\u2019s.<\/p>\n Researchers at the Biggs Institute recognized that leveraging the large, well-characterized Framingham Heart Study cohorts offered an opportunity to address gaps by simultaneously analyzing up to four blood-based biomarkers using flexible modeling approaches and systematic covariate assessment.<\/p>\n They used non-linear modeling, which \u2013 unlike linear models that assume a constant, straight-line rate of change \u2013 uses curves, exponentials and logarithms to map complex relationships in data. On a scatter-plot graph of dots representing values on horizontal and vertical axes, for instance, non-linear points form a curved pattern, meaning the relationship changes in strength or direction across the range of data.<\/p>\n Specifically, the scientists used restricted cubic splines, or RCS, a common technique used in regression analysis to model non-linear relationships between a continuous predictor (a factor influencing an outcome) and a target variable (the outcome).<\/p>\n The RCS revealed a robust non-linear association between sleep duration and p-tau181, with higher levels at eight-and-a-half hours or more, after adjusting for factors including age, sex, sleep apnea, depression, kidney function and apolipoprotein E \u03b54 genotype, a common genetic variant linked to an increased risk of developing late-onset Alzheimer\u2019s and cardiovascular disease.<\/p>\n![\"\"](\"https:\/\/www.newsbeep.com\/us-tx\/wp-content\/uploads\/2026\/07\/sleep-and-dementia-biomarkers-1.jpg\")
<\/a>Panel A shows the sharp non-linear association between sleep duration and p-tau181, a blood-based biomarker of neurodegeneration,, adjusted for age, sex, cohort, APOE \u03b54 status, obstructive sleep apnea, depression and kidney function, but less so for other biomarkers in panels B-D. Shaded areas represent 95% confidence intervals.<\/p>\n