A joint study by several universities and research institutions in Sweden and China has found that people with poor sleep quality tend to have a biological brain age older than their actual age, and elevated levels of inflammation in the body may be partly responsible for this phenomenon.
According to Xinhua News Agency, the Karolinska Institutet in Sweden recently issued a press release stating that the research team analyzed brain MRI data from about 27,500 middle-aged and elderly individuals from the UK Biobank, and used machine learning methods to estimate the biological age of the brain. Unlike chronological age, biological brain age refers to the actual functional and structural state of the brain and reflects the degree of brain aging.
The study used five self-reported sleep factor indicators—chronotype (morning person/night owl), sleep duration, severity of insomnia, snoring status, and daytime sleepiness—to create a composite score for each participant. Based on these scores, participants were divided into three groups: healthy (score ≥4), intermediate (score 2–3), and poor sleep (score ≤1).
The final results showed that for every one-point decrease in sleep quality score, the biological brain age was on average about six months older than the actual age. Overall, people with poor sleep quality had brains that were on average one year older than their actual age.
To further understand the impact of sleep quality on the brain, the research team measured individuals' levels of low-grade inflammation. The results found that inflammation could explain about 10% of the association between poor sleep and accelerated brain aging. Other possible mechanisms linking sleep and brain aging include the negative effects of insufficient sleep on the brain's waste clearance system and cardiovascular health, which can in turn damage the brain.
The researchers recommend that people improve their sleep to protect brain health. “Sleep is a lifestyle factor that can be self-regulated. Healthier sleep helps slow brain aging and cognitive decline.”
This research was jointly conducted by the Karolinska Institutet, the Swedish School of Sport and Health Sciences, Tianjin Medical University, and other universities and research institutions, and was supported by several Swedish research foundations. The relevant findings were recently published in the British journal EBioMedicine.