Poor sleep could age the brain faster, study suggests
A restless night could be making your brain older than it really is, according to new research that sheds light on the powerful role sleep plays in brain health.
Scientists at Karolinska Institutet in Sweden have found that poor sleep habits are linked to brains that appear biologically older than their actual age.
The findings, published in eBioMedicine, suggest that disrupted sleep could accelerate brain ageing and increase the risk of cognitive decline later in life.
The research team analysed brain scans from more than 27,500 middle-aged and older adults who took part in the UK Biobank study.
Participants underwent MRI imaging, and machine learning techniques were used to estimate each person’s “brain age”, a biological measure derived from over a thousand brain imaging features.
When brain age was compared to chronological age, a clear pattern emerged: poor sleep was consistently tied to older-looking brains.
To assess sleep, the researchers developed a score based on five self-reported factors: whether someone was a morning or evening person, average sleep duration, symptoms of insomnia, snoring, and daytime sleepiness.
Based on their scores, participants were categorised into three groups: healthy sleepers, intermediate sleepers, and poor sleepers.
“The gap between brain age and chronological age widened by about six months for every one-point drop in healthy sleep score,” said Abigail Dove, lead author of the study and researcher at Karolinska Institutet’s Department of Neurobiology, Care Sciences and Society. “On average, people with poor sleep had brains that appeared about a year older than their real age.”
The study also probed possible explanations for this accelerated brain ageing. One mechanism appears to be inflammation: blood tests revealed that low-grade inflammation explained just over 10 per cent of the link between poor sleep and older brain age. Inflammation has long been implicated in both ageing and neurodegenerative diseases such as Alzheimer’s.
Other pathways may also play a role.
Sleep is known to be critical for the brain’s waste clearance system, which helps flush out toxic proteins, as well as for cardiovascular health. Disruptions in either could set the stage for premature brain ageing.
While previous studies have shown that poor sleep is associated with dementia, researchers have debated whether disturbed sleep is an early warning sign of the disease or a contributing factor.
The new findings provide evidence that poor sleep itself may actively drive brain changes associated with ageing, rather than simply being a symptom.
“Our results suggest that sleep could be a modifiable risk factor for brain ageing,” Dove noted. “That means promoting healthier sleep habits might be one way to protect the brain and reduce the risk of cognitive decline.”
The researchers caution, however, that their study had limitations. Participants in the UK Biobank tend to be healthier than the general population, which may restrict how widely the findings can be applied, even for the Kenyans and worldwide. Additionally, the sleep data was based on self-reported surveys rather than objective measurements.
Even so, the study adds to a growing body of evidence linking sleep quality to long-term brain health. With sleep being one of the few lifestyle factors people can directly control, the research underscores a simple but powerful message: protecting your sleep may also help protect your brain.
