A LARGE-scale analysis of more than 27,000 adults from the UK Biobank has found that poor sleep patterns are associated with accelerated brain ageing, partly mediated by low-grade systemic inflammation.
Poor sleep and brain health
Sleep health has long been implicated in cognitive decline and dementia risk, but the underlying mechanisms have remained uncertain. In this study, researchers examined how specific sleep behaviours relate to biological ageing of the brain. A “healthy sleep score” was calculated based on five self-reported habits: early chronotype, sleeping 7–8 hours per night, absence of insomnia, no snoring, and no excessive daytime sleepiness. Higher scores reflected healthier sleep. Participants were then classified into three categories: healthy (four or more points), intermediate (two to three points), and poor (one point or less).
Poor sleep accelerates brain ageing
The investigators analysed brain ageing using advanced machine learning applied to over 1,000 brain MRI measures, generating a ‘brain age gap’ (BAG), the difference between brain-predicted age and actual chronological age. After nearly 9 years of follow-up, both intermediate and poor sleepers demonstrated significantly higher BAG values compared with healthy sleepers, indicating accelerated brain ageing.
Specifically, those with intermediate sleep patterns had a BAG increase of 0.25 years, while those with poor sleep showed a larger increase of 0.46 years. Although these figures appear modest, across populations they could translate into meaningful differences in dementia risk and cognitive decline.
Inflammation as a pathway
Importantly, the study also investigated inflammation as a potential pathway. Using the INFLA-score, which assesses low-grade inflammation by combining four blood biomarkers (C-reactive protein, white blood cell count, platelet count, and granulocyte-to-lymphocyte ratio), researchers found that systemic inflammation explained between 7–10% of the relationship between poor sleep and accelerated brain ageing. This suggests that inflammation plays a measurable, but partial, role in linking disrupted sleep to neurological decline.
These findings strengthen evidence that poor sleep is not just a lifestyle inconvenience but a measurable risk factor for accelerated brain ageing. Improving sleep quality may represent a modifiable target to reduce dementia risk and promote healthier ageing of the brain.
Reference
Miao Y et al. Poor sleep health is associated with older brain age: the role of systemic inflammation. EBioMedicine. 2025; DOI:10.1016/j.ebiom.2025.105941.
