Sleep habits shape your brain’s biological age

A new study followed 27,500 adults and linked their everyday sleeping habits with MRI-based estimates of how old the brain appears compared to a person’s chronological age.

The team found that poor sleep patterns age a person’s brain faster than those who sleep more than 8 hours per night.

Scientists calculated a brain age gap by comparing a machine learning estimate of brain age with actual age, using magnetic resonance imaging (MRI) to capture over a thousand features from structure and function. 

Sleep patterns and brain scans

The project was led by Abigail Dove at Karolinska Institutet (KI). Her group studied sleep patterns and brain scans from volunteers in the UK Biobank, a long-running research resource.

The researchers combined five self-reported sleep traits into a single “healthy sleep” score.

These traits were chronotype, sleep duration, insomnia, snoring, and daytime sleepiness. Chronotype refers to whether a person naturally tends to be a morning type or an evening type.

Participants also reported how long they slept, whether they struggled to fall or stay asleep, whether others noticed snoring, and whether they felt sleepy during the day.

The brain scans were processed to estimate brain age from 1,079 MRI-derived features. The difference between estimated brain age and real age defines the brain age gap.

Poor sleep, older brain

“The gap between brain age and chronological age widened by about six months for every 1 point decrease in healthy sleep score. People with poor sleep had brains that appeared on average one year older than their actual age,” said Dove.

The association was stronger in men and in adults younger than 60 at the start of the study. That pattern hints at different vulnerabilities across groups.

Sleep and the immune system interact in both directions, as detailed in a major review. Disruption and lack of healthy rest can raise inflammatory signaling. In turn, inflammation can disrupt sleep.

This study estimated low-grade inflammation from a composite blood score and found it explained just over 10 percent of the sleep-brain age link. That leaves room for other biological pathways.

Sleep deprivation harms heart health

Poor sleep is closely linked to cardiovascular problems such as hypertension and heart disease, conditions that can indirectly affect brain health.

Studies have shown that disrupted or insufficient sleep raises blood pressure and interferes with the body’s ability to regulate blood sugar and cholesterol levels. Over time, these changes can damage blood vessels, reducing blood flow to the brain.

Because the brain relies on a steady supply of oxygen and nutrients carried through the blood, weakened cardiovascular health can accelerate aging processes in brain tissue.

This suggests that it may influence brain age not just through inflammation, but also through its effect on the heart and circulatory system.

Sleep habits and brain aging

Independent research shows that getting about 6 to 8 steady hours of sleep relates to larger gray matter volumes in multiple regions, including the hippocampus and frontal cortex That pattern fits with the score used here, which rewards 7 to 8 hours.

When we’re asleep, the brain’s glymphatic system ramps up movement of fluid that helps clear metabolic waste. Clearance slows when that is cut short or fragmented.

Patients recorded with brain aging revealed health risks, including higher mortality, in population studies that use similar MRI models.

Brain age a useful early signal, not a diagnosis. A higher brain age gap flags departure from typical aging. It is one piece of the puzzle alongside memory tests and other clinical data.

Further research is needed

Participants were healthier on average than the general population. This means that the link between sleep and brain aging may be underestimated.

The patterns were self-reported by test patients, so they may miss changes between workdays and weekends or unrecognized snoring.

Objective tools like actigraphy or home polysomnography would add precision. Timing also matters for cause and effect.

To nail down direction, future work needs repeated measures of sleep, brain markers, and thinking over time.

Sleep for a healthy mind and body

“Since sleep is modifiable, it may be possible to prevent accelerated brain aging and perhaps even cognitive decline through healthier sleep,” said Dove.

If future trials show that improving sleep shifts brain age, that would be important for public health. Other cohorts point the same way.

Midlife adults with clusters of poor sleeping traits showed advanced brain aging years later in the CARDIA cohort.

For now, consistent sleep timing, sufficient nightly sleep, and treatment of snoring or insomnia remain sensible goals supported by biological evidence.

This work adds clear, brain-based evidence that everyday sleep patterns matter.

The study is published in the journal eBioMedicine.

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