A NEW analysis has revealed a non-linear link between sleep duration and dementia biomarkers, with longer sleep, particularly beyond 8.5 hours, associated with higher levels of plasma p-tau181, a key marker of Alzheimer’s disease.
Both short and long sleep duration have been associated with Alzheimer’s disease risk, but the nature of the non-linear relationship between sleep quantity and blood-based biomarkers of Alzheimer’s disease and neurodegeneration has remained understudied. Existing evidence linking sleep duration to dementia risk has remained mixed, with particularly limited research examining blood-based biomarker profiles, and none previously including glial fibrillary acidic protein (GFAP).
Researchers examined associations between self-reported sleep duration and four plasma biomarkers, phosphorylated tau (p-tau)181, total tau (t-tau), neurofilament light chain (NfL), and GFAP, among 2,410 participants.
Restricted cubic spline modelling revealed a non-linear association between sleep duration and p-tau181 (overall p=0.005; non-linearity p=0.002), with higher levels observed at 8.5 hours of sleep or more, after adjustment for age, sex, apolipoprotein E ε4 genotype, sleep apnoea, depression, and kidney function. Total tau showed a similar pattern, although this non-linearity was attenuated after adjustment, while associations for neurofilament light chain were largely explained by kidney function. Shorter sleep duration showed no significant associations with any of the biomarkers assessed.
These findings have suggested that longer sleep duration, particularly beyond 8.5 to 9 hours, may reflect early neurodegenerative processes, given that the association with p-tau181 persisted while associations with neurofilament light chain did not. As this was a cross-sectional study, causality cannot be established, and the findings are considered hypothesis-generating. The authors have suggested that self-reported sleep duration exceeding 9 to 10 hours per night may warrant further sleep and cognitive evaluation, pending validation in prospective studies incorporating objective sleep measures and emerging biomarkers such as p-tau217 and p-tau231.
Young VM et al. Non-linear associations between sleep duration and plasma p-tau181 in the Framingham Heart Study. Alzheimer’s Dement. 2026; 22:e71499.
Featured image: Zembeco on Adobe Stock
Each article is made available under the terms of the Creative Commons Attribution-Non Commercial 4.0 License.
