Poor sleep may accelerate brain aging, new findings suggest
In a large study led by researchers at Karolinska Institutet, scientists explored how everyday sleep habits relate to the aging of the brain. Using data from 27,500 middle-aged and older adults in the UK Biobank, the team estimated brain age with machine learning on more than a thousand MRI-derived brain measures. The goal was to see whether poorer sleep quality is associated with a biologically older brain relative to a person’s chronological age.
How sleep quality was measured
Participants reported five aspects of sleep health: daily timing preference (morning vs. evening chronotype), typical sleep duration, trouble falling asleep, snoring, and daytime sleepiness. Each participant was assigned a sleep quality score and categorized into three groups: good sleepers (score ≥ 4), intermediate sleepers (score 2–3), and poor sleepers (score ≤ 1).
What the study found about brain aging
The researchers found a clear, graded link between sleep quality and brain age. Specifically, every one-point decline in sleep quality was associated with roughly six additional months of brain aging. On average, those classified as poor sleepers showed a brain that appeared about one year older than their actual chronological age. Abigail Dove, a lead investigator at Karolinska Institutet, emphasized the magnitude: “each point drop in sleep quality translated into meaningful aging of the brain.”
Could inflammation explain the connection?
To probe mechanisms, the team looked at low-grade systemic inflammation, a known feature of many chronic conditions. They found that inflammation could account for a little over 10 percent of the association between poor sleep and older-appearing brains. This points to inflammation as one plausible pathway linking sleep and brain aging, although it is unlikely to tell the whole story.
Other potential pathways
Beyond inflammation, several other mechanisms may contribute. Sleep is thought to support the brain’s waste clearance system, helping remove neurotoxic proteins—an essential process during deep rest. Poor sleep could impair this clearance, allowing harmful substances to accumulate. Additionally, sleep disturbances are linked to cardiovascular health risks, and vascular problems can, in turn, affect brain health. These interconnected processes may collectively drive faster brain aging in those with suboptimal sleep.
Limitations and public health implications
The UK Biobank cohort tends to be healthier than the general population, which may influence generalizability. Moreover, sleep measures were self-reported, which can introduce biases. Despite these caveats, the study adds to growing evidence that sleep health is not just a nightly habit but a potential determinant of brain aging. Since sleep patterns can be modified, these findings carry meaningful public health implications.
What this means for everyday life
While more research is needed to establish causality, prioritizing good sleep could be a practical strategy to support brain health. Public health guidance often recommends regular sleep schedules, avoiding stimulants late in the day, managing sleep-disordered breathing, and creating a sleep-friendly environment. For individuals with persistent sleep problems or snoring, seeking medical evaluation may help address underlying issues that could contribute to brain aging over time.
Future directions
The study demonstrates the value of combining large-scale imaging with machine learning to understand brain aging. Future work may explore whether interventions that improve sleep quality can slow apparent brain aging and whether reducing inflammation or improving waste clearance during sleep can translate into tangible cognitive benefits as people age.
