Poor Sleep May Accelerate Brain Aging, Large Study Suggests

Sleep has long been known to play a critical role in restoring the body and protecting the brain, but new research suggests that the cost of disrupted sleep may be even higher than previously thought. In a study involving more than 27,000 UK adults between the ages of 40 and 70, researchers found that people with poor sleep habits had brains that appeared significantly older than their actual age. The findings, based on advanced brain imaging and artificial intelligence analysis, add to growing evidence that poor sleep can accelerate cognitive decline and increase the risk of dementia and other neurological diseases.

The concept of an "older-looking brain" refers to biological age, which does not always match chronological age. Using more than 1,000 imaging markers from MRI scans—including brain tissue loss, cortical thinning, and blood vessel damage—scientists trained a machine learning model to estimate brain age. When applied to the full study population, the model revealed a consistent gap between poor sleepers and those with healthy sleep patterns. Participants with poor sleep profiles had brains that appeared nearly one year older than expected, while those with healthier sleep habits showed no significant difference between biological and chronological brain age.

The research team created a "healthy sleep score" based on five self-reported factors: chronotype (morning vs. evening preference), sleep duration, insomnia symptoms, snoring, and daytime sleepiness. Those with four or five healthy sleep traits had the healthiest profiles, while individuals with only one or none were categorized as having poor sleep health. Notably, the study found that late chronotypes and abnormal sleep duration—whether too little or too much—were the strongest predictors of faster brain aging. The difference was significant, with brain age diverging by around six months for every one-point drop in sleep score.

Although a one-year increase in brain age may seem modest, researchers caution that even small accelerations can have long-term consequences. Faster brain aging has previously been linked to memory decline, dementia, and premature mortality. The findings highlight the importance of sleep as a modifiable risk factor, and researchers emphasize that lifestyle changes—such as maintaining a consistent bedtime, limiting caffeine and screen use before sleep, and creating a dark and quiet environment—can improve sleep quality and potentially protect the brain.

The study also explored potential biological explanations for the connection between sleep and brain aging. Blood samples from participants showed that higher levels of inflammation accounted for roughly 10 percent of the observed link. Chronic inflammation is known to damage blood vessels, promote the buildup of harmful proteins, and accelerate the death of brain cells. Other mechanisms may also contribute, including impaired function of the glymphatic system—the brain’s natural waste removal process, which is most active during sleep—as well as increased risks of conditions such as diabetes, obesity, and cardiovascular disease, all of which harm brain health.

As one of the largest and most detailed studies of its kind, the findings underscore the role of sleep in shaping how the brain ages. While it is impossible to halt the process of brain aging altogether, the research shows that individuals can influence its pace through lifestyle and behavior. The message from scientists is clear: prioritizing sleep is not a luxury, but a key factor in maintaining long-term brain health and reducing the risk of neurodegenerative disease.