Lack of sleep can accelerate brain aging

People who sleep poorly are more likely than others to have brains that look older than they actually are.

This is the conclusion of a study based on brain imaging from the Karolinska Institute (Sweden) and conducted in collaboration with researchers from the Swedish School of Sport and Health Sciences, Tianjin Medical University, and Sichuan University (China), among others.

Poor sleep has been linked to dementia, but it's unclear whether poor sleep habits contribute to its development or are early symptoms of the disease. In a new study, researchers at the Karolinska Institutet analyzed the relationship between sleep characteristics and the apparent age of the brain relative to its chronological age.

The study, published in the journal eBioMedicine, included 27,500 middle-aged and older individuals from the UK Biobank who underwent brain MRI. Using machine learning, the authors estimated the biological age of the brain based on more than 1,000 brain phenotypes obtained through MRI.

Brain inflammation

Participants' sleep quality was assessed based on five self-reported factors: chronotype (being a morning or evening person), sleep duration, insomnia, snoring, and daytime sleepiness. They were divided into three groups: healthy sleep (at least four points), intermediate sleep (two to three points), or poor sleep (up to one point).

“The gap between brain age and chronological age widened by approximately six months for every point decrease in the healthy sleep score,” explains Abigail Dove, a researcher at the Department of Neurobiology, Attention Sciences and Society at Karolinska Institutet. “People with poor sleep had brains that, on average, looked a year older than their actual age.”

Read also

To understand how lack of sleep can affect the brain, researchers also examined levels of mild inflammation in the body. They found that this could explain just over 10% of the relationship between lack of sleep and older brain age.

“Our findings provide evidence that lack of sleep may contribute to accelerated brain aging and point to inflammation as one of the underlying mechanisms,” Dove says. “Because sleep is modifiable, it may be possible to prevent accelerated brain aging and even cognitive decline through healthier sleep.”

Other possible mechanisms that could explain the association include negative effects on the brain's waste disposal system, which is primarily active during sleep, or the fact that lack of sleep affects cardiovascular health, which, in turn, can negatively impact the brain.