Regularly sleeping more than eight and a half hours a night could be sign of early Alzheimer's

By MARTI STELLING, HEALTH REPORTER Published: 00:10, 2 August 2026 | Updated: 00:18, 2 August 2026 Regularly sleeping more than eight and a half hours each night could be linked to early Alzheimer’s-related brain changes, research suggests. Previous studies have linked both short and long sleep duration with Alzheimer’s disease, the most common cause of dementia in the UK. Now a study from US-based researchers has found that people who reported sleeping more than eight and a half hours a night had higher blood levels of p-tau181 –a biomarker strongly associated with Alzheimer’s disease. The study, published in the journal Alzheimer’s & Dementia, analysed 2,410 participants from the Framingham Heart Study, with an average age of 70 years. Levels of the biomarker rose more sharply among those sleeping more than ten hours. This remained the case even after researchers adjusted for factors such as age, sex, sleep apnoea and depression. The authors suggested that self-reported sleep duration of more than nine to ten hours per night may warrant further assessment of sleep and cognitive health. ‘We knew from the existing literature that the relationship between sleep and these biomarkers was unlikely to be simple, and that’s exactly what we found,’ said the study’s author, Dr Vanessa Young, a postdoctoral research fellow at the Glenn Biggs Institute for Alzheimer’s and Neurodegenerative Diseases at UT Health San Antonio. Researchers said that the findings do not suggest that sleeping longer causes Alzheimer’s disease.  Regularly sleeping more than eight and a half hours a night could be a sign of early Alzheimer's, a study has suggested (File image) Instead, they believe longer sleep could be an early behavioural sign of underlying brain degeneration – and noted that long-term studies are needed to clarify the relationship between sleep duration and Alzheimer’s disease. The NHS recommends adults up to the age of 65 should sleep for seven to nine hours per night, while those over 65 should aim for seven to eight hours. Around one million people live with dementia in the UK, with one in 14 over-65s affected.  The devastating illness impacts language, reasoning, memory and daily tasks.