- Medical News Today has recently covered several pieces of research that support a strong link between sleep and dementia risk.
- One of these studies, using MRI scans, found that people with a weaker glymphatic system—which clears toxins from the brain during sleep—have a higher risk of dementia.
- Another study found that moderate to severe obstructive sleep apnea may raise the risk of tiny brain bleeds, which could increase the chances of dementia and stroke.
- And another study suggested that people with chronic insomnia may be at a greater risk of developing dementia or mild cognitive impairment, which has been linked to faster brain aging.
Sleep is an important partTrusted Source of overall health. The amount and quality of sleep people get can affect various aspects of health, including the heart and circulatory system, the respiratory system, and cognitive functions such as thinking and memory.
Recent research has found that getting enough sleep and having good quality sleep may also play an important role in an individual’s risk of developing dementia.
In this study roundup, Medical News Today shares three key findings from the latest research that highlight and further confirm the connection between sleep and dementia risk.
Poor sleep, high blood pressure may increase dementia risk
A studyTrusted Source from October 2025 found that people with an impaired glymphatic system may have a higher risk of developing dementia.
The glymphatic system is a newly discovered waste clearance system. It is most active during sleep. During this time, the glymphatic system removes toxins and waste materials, including those associated with dementia, from the central nervous system.
This study suggests that improving the glymphatic system may be a powerful tool in reducing the risk of dementia.
“These findings are largely expected, building on a growing body of research that implicates impaired cerebrospinal fluid (CSF)Trusted Source dynamics, often referred to as the ‘glymphatic system’, in dementia. Animal studies have long shown that disrupted CSF flow hampers the clearance of toxic proteins such as amyloid beta and tau, which are central to Alzheimer’s disease pathology. What makes this study significant is that it provides large-scale, human-based evidence from over 45,000 participants in the UK Biobank, confirming that MRI markers of CSF dysfunction […] are associated with higher dementia risk.”
— Steve Allder, MD, consultant neurologist at Re:Cognition Health, who was not involved in the study.
The researchers applied specific algorithms to MRI scans of 45,000 adults. In doing so, they identified three biomarkers linked to glymphatic function and predicted dementia risk over the following decade.
“This newly published study uses brain imaging to look at different snapshots of the glymphatic system in about 45,000 people from the large UK Biobank. They found three biomarkers related to CSF movement that, in the study population, were predictive of new cases of dementia. These factors were also related to the ways in which heart health issues can contribute to dementia risk,” Ozama Ismail, PhD, Director of scientific programs at the Alzheimer’s Association, which published the study in its journal, said.
Allder explained to Medical News Today how improving the flow of CSF may decrease the risk of dementia.
“There are emerging strategies to support or improve glymphatic clearance. Good cardiovascular health is key — maintaining optimal blood pressure, managing diabetes, and exercising regularly all enhance vascular pulsatility and CSF flow. Quality sleep is also critical, as glymphatic clearance is most active during deep sleep. Avoiding excessive alcohol, staying hydrated, and possibly using interventions that improve arterial elasticity (e.g., aerobic fitness, dietary omega-3s) may further help preserve waste clearance efficiency,” he said.
Sleep apnea may increase dementia and stroke risk
Another studyTrusted Source, also from October 2025, that involved an 8-year follow-up with more than 1,400 participants, found there may be an increased risk of cerebral microbleeds among adults with severe obstructive sleep apnea (OSA).
Cerebral microbleeds may increase the risk of experiencing dementia and symptomatic strokes. The authors of the study suggest that addressing OSA may help prevent dementia and stroke among older adults.
Cerebral microbleeds involve a buildup of certain blood products in the brain and may be more common in older adults.
The researchers found that the highest incidence of cerebral microbleeds was in those with moderate to severe OSA. At the end of the study, the risk of cerebral microbleeds in this group was found to be nearly double those without OSA.
The study author Chol Shin, MD, PhD, Institute of Human Genomic Study, College of Medicine, Korea University, highlighted the following to Medical News Today about the study’s findings:
“From a Korean population, sleep studies and brain MRIs over eight years revealed that adults with moderate to severe obstructive sleep apnea (OSA) were more than twice as likely to develop microbleeds in the brain than those without sleep apnea.”
The study was insightful. However, there were also limitations. Future research can further explore the connection between moderate to severe OSA and cerebral microbleeds.
While more research on the benefits of OSA treatment is needed, Stephen Carstensen, doctor of dental surgery and sleep expert, who was not involved in the study, also noted the following to Medical News Today:
“This study correlates higher levels of diagnosed sleep apnea with a bit more than double the chances of having a brain microbleed. This study gives solid medical-science reasons why getting diagnosed and treated early in life can help preserve brain health over the long term. This study was not about any protective effects of therapy, so we cannot use it to assure people that managing their sleep apnea with a dental device or CPAP lowers their risk of stroke, but other studies have shown that result.”
Chronic insomnia may raise dementia risk by 40%
And lastly, a study from September 2025 found that people with chronic insomnia may be at a greater risk of developing mild cognitive impairment (MCI) or dementia than those without chronic insomnia. This may be associated with faster brain aging.
The study included 2,750 participants with an average age of 70, all of whom were cognitively healthy at the study’s outset. Around 16% of them had chronic insomnia. The researchers tracked the participants for an average of 5.6 years. During that time, they were asked about their sleeping patterns, took thinking and memory tests, and had brain scans to look for white matter hyperintensitiesTrusted Source and beta-amyloid plaques, which are associated hallmarks of Alzheimer’s disease.
Diego Z. Carvalho, MD, MS, sleep medicine specialist at the Mayo Clinic in Minnesota and lead author of this study, told Medical News Today, “We focused on studying the impact of insomnia on different markers of brain health to understand how insomnia may be related to cognitive decline. Is it only through Alzheimer’s disease-related changes like amyloid, or also through cerebrovascular pathways affecting our white matter?”
Researchers discovered at the study’s conclusion that participants with chronic insomnia had a 40% higher chance of developing dementia or MCI than participants with non-chronic insomnia, which is reportedly equivalent to 3.5 additional years of aging.
“In our models, the impact of insomnia on the risk of MCI/dementia was higher than having two cardiometabolic conditions like hypertension and diabetes, or being 3.5 years older than your actual age, which are known risk factors,” Carvalho explained. (https://www.medicalnewstoday.com/articles/medical-myths-how-much-sleep-do-we-need#2-Daytime-naps-are-unhealthy)
