Poor Sleep Linked to Faster Brain Aging, Study Finds

People who sleep poorly may have brains that appear older than their actual age, according to a large brain imaging study conducted by researchers at Karolinska Institutet and published in eBioMedicine. The study suggests that increased inflammation in the body may partly explain this link.

Poor sleep has long been associated with dementia, but it remains unclear whether unhealthy sleep patterns actively contribute to the disease or simply act as early warning signs. To investigate further, researchers analyzed sleep quality and brain aging among 27,500 middle-aged and older adults from the UK Biobank. Participants underwent MRI scans, and researchers used machine learning to estimate the biological age of their brains based on over a thousand imaging markers.

Measuring Sleep Quality

Participants reported on five sleep-related factors: chronotype (morning or evening preference), sleep duration, insomnia, snoring, and daytime sleepiness. Based on these, they were scored and grouped into three categories: healthy sleepers (≥4 points), intermediate sleepers (2–3 points), and poor sleepers (≤1 point).

The results revealed that the gap between brain age and chronological age widened by about six months for every one-point decrease in sleep score. On average, individuals with poor sleep had brains that appeared one year older than their true age.

Role of Inflammation

To explore the biological mechanism, the researchers also examined levels of low-grade inflammation. They found that inflammation accounted for just over 10 percent of the connection between poor sleep and accelerated brain aging.

“Our findings provide evidence that poor sleep may contribute to accelerated brain aging and point to inflammation as one of the underlying mechanisms,” said Abigail Dove, researcher at the Department of Neurobiology, Care Sciences and Society, Karolinska Institutet. “Since sleep is modifiable, it may be possible to prevent accelerated brain aging and perhaps even cognitive decline through healthier sleep.”

Other Possible Explanations

The researchers note that other factors may also play a role. Poor sleep could impair the brain’s waste clearance system, which functions mainly during sleep, or affect cardiovascular health, which in turn impacts brain health.