Sleep Duration and Quality May Be Associated With Alzheimer-Related Biomarkers

Sleep duration and quality may be associated with fluid biomarkers present in Alzheimer disease, wrote authors of a systematic review published in Sleep Medicine Reviews. Specifically, short sleep duration was associated with higher levels of Alzheimer disease-related biomarkers.¹

Poor sleep quality and delayed rapid eye movement (REM) sleep have previously shown some association with the likelihood of developing dementia. Two large longitudinal studies determined that short sleep duration in older adulthood is strongly associated with increased dementia risk and mortality.

In a US study of more than 2800 adults aged 65 and older, those who slept fewer than 5 hours per night were twice as likely to develop dementia and twice as likely to die within 5 years compared with those sleeping 6 to 8 hours. These trends remained present even after adjusting for demographic and health factors. Similarly, a European study of nearly 8000 participants showed that consistently sleeping 6 hours or less at ages 50, 60, and 70 years was linked to an approximately 30% higher risk of dementia than sleeping 7 hours, with results remaining robust after controlling for social, behavioral, cardiometabolic, and mental health variables and supported by objective sleep measurements in a subset of participants.²

Further, research published in Alzheimer’s & Dementia suggested that delayed entry into rapid eye movement (REM) sleep may be an early indicator of Alzheimer disease and related dementias, as prolonged REM latency was associated with greater amyloid and tau burden and reduced brain-derived neurotrophic factor. Participants who reached REM sleep later—often more than 193 minutes after sleep onset—were more likely to have Alzheimer disease and demonstrated significantly higher levels of amyloid beta and phosphorylated tau, even after adjustments were made for demographic, genetic, cognitive, and health factors. Interestingly, total sleep time and sleep efficiency were not linked to dementia biomarkers. The findings support growing evidence that disrupted sleep architecture, particularly delayed or reduced REM and slow-wave sleep, may impair memory consolidation and contribute to neurodegeneration, highlighting REM sleep as a potential early marker and modifiable target for dementia risk, though intervention trials are still needed to confirm whether improving REM sleep can alter disease progression.³

New Research Identifies Fluid Biomarkers

The current systematic review continued the relationships between self-reported or objective sleep duration and Alzheimer disease, but this research specifically identified fluid biomarkers of Alzheimer disease pathology and neurodegeneration: cerebrospinal fluid or blood Aβ, p-tau181, t-tau, NfL and GFAP. The investigators searched PubMed, SCOPUS, and CINAHL from inception to September 2024. Twenty studies met inclusion criteria (13 studies evaluating cerebrospinal fluid biomarkers; 7 evaluating blood biomarkers).¹

The authors wrote that, although many studies did not report any associations, some trends emerged. Short sleep duration was associated with higher cerebrospinal fluid t-tau and p-tau181 and lower cerebrospinal fluid or blood Aβ42 across multiple studies. Additionally, longer sleep duration demonstrated more variable associations, with some suggesting either worse or better biomarker profiles (eg, higher and lower fluid t-tau, p-tau181, or Aβ42).

Further, 2 studies investigating nonlinear relationships identified U-shaped associations, suggesting both short (≤5–6 hours) and long (≥8 hours) sleep durations are associated with altered biomarker profiles. The predominantly cross-sectional and high heterogeneity of the available evidence, as well as the relatively small number of studies by individual biomarker (especially for NfL and GFAP) limit conclusions about sleep-biomarker relationships. The authors suggested that future research should investigate emerging blood-based biomarkers and explore temporal associations between sleep duration and Alzheimer disease biomarker changes.¹

REFERENCES

1. Young VM, Zeynoun J, Ruiz Laza A, Salardini A, Frei CR, Gaspard C, Kautz T, Macedo E Cordeiro T, Pase MP, Gelfond J, Himali JJ, Teixeira AL, Seshadri S, Baril AA. Association between sleep duration and fluid biomarkers of Alzheimer's disease: A systematic review. Sleep Med Rev. 2026 Jan 23;86:102242. doi: 10.1016/j.smrv.2026.102242. Epub ahead of print. PMID: 41610733.

2. Budson AE. Sleep well — and reduce your risk of dementia and death. Harvard Health Publishing. May 3, 2021. Accessed January 30, 2026. https://www.health.harvard.edu/blog/sleep-well-and-reduce-your-risk-of-dementia-and-death-2021050322508

3. McGovern G. People Who Achieve REM Sleep Later Might Be Experiencing Early Symptom of Alzheimer Disease. Pharmacy Times. February 3, 2025. Accessed January 30, 2026. https://www.pharmacytimes.com/view/people-who-achieve-rem-sleep-later-might-be-experiencing-early-symptom-of-alzheimer-disease