While the link The link between impoverished sleep and dementia has long been known, but it was unclear whether impoverished sleep habits could cause dementia or whether impoverished sleep was an early symptom of dementia. However, new research he revealed it to sleep quality can have a direct impact on the speed at which the brain is getting old.
“Our findings provide evidence that poor sleep may contribute to accelerated brain aging,” he added. explains Abigail Dove, a neuroepidemiologist at the Karolinska Institute in Sweden, “and points to inflammation as one of the underlying mechanisms.”
High correlation with night owl lifestyle and snoring
Scientists assessed the quality of their sleep in five dimensions in 27,500 middle-aged and older people (average age 54.7 years) registered in the British Biobank (a research institute conducting long-term follow-up studies on the impact of genetic predispositions and lifestyle on diseases). About nine years later, the participants’ brains were scanned using MRI and machine learning models were used to estimate their biological brain age.
The researchers assessed sleep quality based on chronotype (morning or evening), sleep duration, presence or absence of insomnia, presence or absence of snoring, and daytime sleepiness. Using this data, they divided the participants into three sleep patterns and found that 41.2% slept soundly, 3.3% visibly slept poorly, and 55.6% fell into the middle group.
The analysis showed that for each decrease in the robust sleep score, the difference between brain age and chronological age increased by about six months. In the group with the worst sleep quality, their brains were found to be about a year older than their chronological age. This suggests that differences in sleep duration and sleep habits can significantly impact the rate of brain aging.
Scientists have found that a nocturnal lifestyle, unhealthy sleep duration (over 7-8 hours) and snoring habits are particularly strongly linked to brain aging. They also found that five factors that determine sleep quality work together. For example, insomnia can lead to excessive daytime sleepiness, and a nocturnal lifestyle can lead to less sleep time.
Impoverished sleep leads to chronic inflammation in the body
To understand the mechanism by which impoverished sleep affects the brain, the research team also measured levels of delicate inflammation in the body. Specifically, they used a combination of biomarkers such as C-reactive protein levels, white blood cell and platelet counts, and the granulocyte-to-lymphocyte ratio (a type of white blood cell) to analyze the role of inflammation in the relationship between sleep patterns and brain aging.
The results confirmed that higher levels of inflammation in the body tend to escalate brain age. Mediation analysis (a method of analyzing the influence of intermediate variables in the causal relationship between two variables) found that inflammation explained approximately 7% of the association between indirect sleep patterns and brain aging, and more than 10% of the association with impoverished sleep patterns. In other words, it is highly likely that impoverished sleep quality facilitates chronic inflammation in the body, which in turn accelerates brain aging.
In addition to inflammation, there are several other ways that impoverished sleep can negatively impact the brain. One of them is its negative impact on the glymphatic system, which primarily removes metabolic products from the brain during sleep. If toxic substances from the brain are not effectively removed during sleep, it can impair the functioning of nerve cells in the long term. Researchers have also indicated that impoverished sleep can worsen cardiovascular health, which indirectly damages blood flow and tissue in the brain.
This story originally appeared on WIRED Japan and has been translated from Japanese.