Why sleep quality may influence brain aging
Emerging evidence suggests that how well we sleep might not only affect how rested we feel, but also how quickly our brains age. In a large UK-based study led by researchers at Karolinska Institutet, scientists explored whether unhealthy sleep patterns are connected to an older-looking brain, as measured by biological age derived from MRI scans. They also investigated whether systemic inflammation could help explain this relationship.
How the study was conducted
The analysis included 27,500 middle-aged and older adults from the UK Biobank who underwent brain magnetic resonance imaging (MRI). Researchers used machine learning to estimate each person’s brain age, drawing on more than a thousand neuroimaging features. This approach yields a biological brain age that may diverge from chronological age, offering insight into individual differences in brain aging.
How sleep quality was assessed
Disease researchers assessed sleep quality using five self-reported factors: circadian preference (morning or evening chronotype), average sleep duration, difficulty falling asleep, snoring, and daytime sleepiness. Based on these responses, participants were categorized into three groups: good sleep (score of ≥4), intermediate sleep (score of 2–3), and poor sleep (score ≤1).
“We found that each point decrease in sleep quality corresponded to about a six-month acceleration in brain aging,” said Abigail Dove, the lead author and researcher at Karolinska Institutet. “Overall, those with poor sleep looked about one year older in brain age than their actual chronological age.”
The role of systemic inflammation
The researchers examined whether low-grade inflammation in the body could explain part of the link between sleep and brain aging. They found that inflammation could account for a little over 10% of the association between poor sleep and older brain age. This suggests that inflammation is one of several mechanisms through which sleep health may influence brain aging.
What this might mean for brain health
The findings add to a growing picture in which sleep is a modifiable factor that could influence cognitive trajectories. If poor sleep contributes to faster brain aging, improving sleep quality might help slow the pace of age-related brain changes and potentially reduce the risk of cognitive decline in later life. The identification of inflammation as one piece of the puzzle also points toward potential therapeutic avenues aimed at reducing systemic inflammation as part of maintaining brain health.
Other possible mechanisms worth exploring
Beyond inflammation, several other pathways could link sleep and brain aging. For instance, sleep is thought to support the brain’s waste-clearance system (glymphatic flow), which clears toxins accumulated during wakefulness. Sleep disturbances could impair this cleaning process, potentially contributing to neurodegenerative changes. Additionally, sleep patterns influence cardiovascular health, and impaired heart and blood vessel function can, in turn, affect brain health over time.
Strengths, limitations, and implications for the public
The UK Biobank provides a large, well-characterized sample, yet participants are generally healthier than the broader population, which may affect how broadly the results apply. A notable limitation is that sleep was self-reported, which can introduce reporting biases. Despite these caveats, the study highlights sleep health as a potentially important, modifiable factor in brain aging, with inflammation offering a plausible biological link. The work was a collaborative effort involving researchers from Sweden, China, and the United Kingdom, and was published in eBioMedicine (online October 1, 2025).
Practical takeaways
- Aim for a consistent sleep schedule and adequate sleep duration aligned with your needs.
- Address sleep-disordered breathing or snoring with a healthcare provider, as treating sleep problems may benefit brain health.
- Develop good sleep hygiene: limit caffeine late in the day, reduce screen-based stimulation before bedtime, and create a comfortable sleep environment.
- Engage in regular physical activity, which supports both sleep quality and cardiovascular health.
- If you notice persistent sleep problems, discuss them with a clinician to explore potential sleep disorders and their impact on brain health.
Bottom line
Although more work is needed to confirm causality, this study adds to the evidence that poor sleep health is linked to an older-looking brain, with inflammation contributing to the connection. Since sleep habits can be improved, prioritizing healthy sleep may be a practical strategy to support brain aging and cognitive vitality as we age.
