A new Swedish study from the Karolinska Institutet in Stockholm has examined how sleep quality relates to the brain’s biological age.
Researchers analyzed data and brain scans from 27,500 adults and older participants in the UK Biobank, a large British health database.
Using machine learning, they calculated each participant’s brain age based on more than a thousand different measurements.
Participants also completed a questionnaire about their sleep habits, including sleep duration, difficulty falling asleep, snoring, and daytime fatigue.
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Based on their responses, they were divided into three groups: good, moderate, and poor sleep.
The results showed that individuals with poor sleep had brains that appeared, on average, one year older than their actual age.
Inflammation may play a role
Previous research published in Sleep has linked poor sleep to cognitive decline and dementia.
The new study builds on that evidence, showing that poor sleep is associated with a measurably older-looking brain, and that inflammation in the body may help explain the connection.
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The researchers found that low-grade inflammation accounted for about ten percent of the relationship between sleep and brain age.
This suggests that inflammation may be one of the mechanisms through which sleep influences the brain.
According to researcher Abigail Dove from the Karolinska Institutet, the findings support the theory that poor sleep can contribute to accelerated brain aging.
She adds that, since sleep is a modifiable factor, improving sleep habits could potentially slow this process.
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Experts urge caution
Not all scientists agree with the conclusions. Anders Martin Fjell, professor of cognitive psychology at the University of Oslo, argues that the method used to estimate brain age does not necessarily reflect actual aging.
He also points out that the study is based on cross-sectional data, which cannot determine whether poor sleep causes changes in the brain, or if the reverse is true.
Sleep researcher Ingvild West Saxvig from the National Centre for Sleep Medicine (SOVno) acknowledges the study’s weaknesses but notes that the large sample size provides a strong foundation for identifying a general link between sleep and brain health.
She emphasizes that inflammation could be a key factor and that several other studies have reached similar conclusions.
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Although the mechanisms are not yet fully understood, Saxvig believes there is already sufficient evidence to recommend prioritizing sleep as part of a healthy lifestyle.
This article is based on information from Forskning.no, Sleep og Karolinska Institutet.
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