Lack of sleep accelerates brain aging

This conclusion was reached by scientists from the Karolinska Institute (Sweden) after analysing data from almost 28,000 people. The results of the large-scale study were published in the scientific journal eBioMedicine.

The study involved more than 27,500 middle-aged and elderly people from the British Biobank. All of them underwent MRI scans of the brain. Using machine learning algorithms, scientists calculated the so-called biological age of the brain - based on more than a thousand phenotypes derived from the scans.

The results were alarming: those who slept poorly had brains that looked, on average, a year older than their well-slept peers.

Participants filled out questionnaires on their own, where they assessed five sleep parameters:

• chronotype (lark or owl),

• sleep duration,

• presence of insomnia,

• snoring,

• daytime sleepiness.

Based on these data, participants were divided into three groups:

• healthy sleep (4-5 points),

• average (2-3 points),

• poor sleep (0-1 points).

Each 1-point drop in the sleep scale corresponded to an acceleration of brain aging by about 6 months, explains the study's lead author, Dr Abigail Dove of the Karolinska Institute.

The scientists also measured levels of low-level systemic inflammation in the participants' bodies. The results showed that inflammation could explain about 10 per cent of the link between poor sleep and premature brain ageing.

"Our findings suggest that poor sleep may contribute to accelerated brain aging and that inflammation may be one of the key mechanisms," commented Dove. "Since sleep is a factor that can be controlled, this opens the door to possible prevention of cognitive decline."

The researchers note that accelerated brain aging may be linked to several mechanisms:

• a disruption of the brain's clearing of waste products, which is active during the sleep phase;

• the negative impact of sleep on the cardiovascular system, which affects brain function;

• chronic stress accompanying insomnia.

It is important to note that the study is based on self-reported sleep, and participants in the British Biobank are generally healthier than the average UK population. This may limit the universality of the findings.

Nevertheless, the work was carried out in collaboration with leading universities including Tianjin Medical University and Sichuan University (China), making it one of the most comprehensive to date.