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Dr Steve Allder, consultant neurologist at Re:Cognition Health, recently shared his insight with Medical News Today on emerging research that strengthens the link between sleep and dementia risk.
The findings echo themes he explores in his TEDx Talk, Reimagining Dementia, where he discusses how sleep, brain clearance and the glymphatic system may play a far more central role in cognitive health than previously recognised.
Sleep and the brain: an increasingly clear connection
Sleep has long been understood as essential for overall health, influencing cardiovascular function, metabolism and immune regulation. Increasingly, research is showing that sleep quality and duration are also deeply tied to long-term brain health. A recent Medical News Today roundup highlights three significant studies that collectively reinforce the idea that disrupted sleep may meaningfully increase dementia risk.
At the heart of this research is the glymphatic system – a waste-clearance network in the brain that becomes most active during deep sleep. This system helps remove toxic proteins such as amyloid beta and tau, which are closely linked to Alzheimer’s disease.
The glymphatic system and dementia risk
One large study published in October 2025 analysed MRI scans from more than 45,000 adults in the UK Biobank. Researchers identified imaging markers associated with impaired glymphatic function and found that individuals with weaker clearance systems were at higher risk of developing dementia over the following decade.
Dr Allder described these findings as an important confirmation of long-standing hypotheses. While animal studies have repeatedly shown that disrupted cerebrospinal fluid (CSF) flow impairs toxin clearance, this research provides large-scale, human evidence linking glymphatic dysfunction to dementia risk.
Crucially, the study also highlighted how cardiovascular health interacts with brain clearance. According to Dr Allder, factors such as optimal blood pressure, good vascular elasticity and regular aerobic exercise help drive the pulsatile CSF movement required for effective glymphatic function. Quality sleep, hydration and avoiding excessive alcohol also play a role – themes he expands on extensively in Reimagining Dementia, where he argues for a broader, systems-based approach to brain health.
Sleep apnoea, microbleeds and stroke risk
Another study featured by Medical News Today focused on obstructive sleep apnoea (OSA), following more than 1,400 participants over eight years. The researchers found that adults with moderate to severe OSA were nearly twice as likely to develop cerebral microbleeds – tiny areas of bleeding in the brain that are associated with increased risk of both dementia and stroke.
The findings suggest that untreated sleep apnoea may contribute to silent but cumulative vascular damage in the brain. While the study did not directly assess whether treating OSA reduces dementia risk, experts emphasised that early diagnosis and management may be important for long-term brain protection.
This aligns with a growing recognition that dementia risk is not driven by Alzheimer’s pathology alone, but also by vascular health, an idea central to modern neurology.
Chronic insomnia and accelerated brain ageing
The third study examined chronic insomnia in older adults who were cognitively healthy at baseline. Over an average follow-up of 5.6 years, researchers found that those with persistent insomnia had a 40% higher risk of developing mild cognitive impairment or dementia compared to those without chronic sleep difficulties.
Brain imaging revealed greater white matter changes and markers of neurodegeneration, suggesting that insomnia may accelerate brain ageing through both neurodegenerative and vascular pathways. Notably, the increased risk associated with insomnia was comparable to being 3.5 years older, and greater than having conditions such as hypertension or diabetes.
A shift in how we think about dementia prevention
Taken together, these studies point to an important shift: sleep is no longer a passive lifestyle factor, but an active biological process that supports brain maintenance and resilience. As Dr Allder highlights in both his clinical commentary and TEDx Talk, protecting sleep may be one of the most accessible, yet underappreciated, strategies for reducing dementia risk.
Rather than focusing solely on late-stage disease treatment, this growing body of research supports earlier, preventative approaches centred on sleep quality, cardiovascular health and brain clearance.
In reimagining dementia, sleep may prove to be one of the most powerful tools we already have.
Read the full article: :https://www.medicalnewstoday.com/articles/sleep-quality-insomnia-sleep-apnea-increase-dementia-risk-latest-evidence#Poor-sleep-high-blood-pressure-may-increase-dementia-risk
Watch the TEDx Talk: https://www.youtube.com/watch?v=rNaCkui7j2Y&t=2s
