Long nights of sleep could lead to higher levels of an Alzheimer’s-related protein in the blood, a UT Health San Antonio study found.
The finding came after studying 2,410 participants and tracking the relation between their sleep duration and the prevalence of a modified form of tau protein, a distinguishable marker of Alzheimer’s disease.
The sharp uptick in association between the protein and sleep came when an individual slept more than 10 hours, though it was first noticeable beginning at eight-and-a-half to nine hours of sleep.
“A lot of people worry about whether their sleep habits are affecting their brain health,” Young said. “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.”
The study participants came from the Framingham Heart Study, a community-based cohort study of residents in Massachusetts. More than 55% of its participants were women, with all participants averaging an age of 70.
The findings come after a study in 2025 found that sleeping nine hours or more a night had a negative impact on cognitive performance, especially for people with depression. This latest study additionally incorporated different health factors and blood-based biomarkers.
More research is needed, but so far researchers concluded the long sleep is a “potential behavior marker” of the elevated protein that is a hallmark to Alzheimer’s, according to a news release.
“If you regularly find yourself sleeping nine to 10 hours or more a night, it may be worth mentioning to your doctor as a useful conversation starter about your sleep quality and overall brain health,” Young said.