Poor sleep isn't just about fatigue and irritability. A new study from scientists at Karolinska Institutet in Sweden has found that chronic sleep deprivation can make the brain look older than its actual biological age—sometimes by almost a year. The finding underscores how critical sleep hygiene is to maintaining cognitive health.
How sleep deprivation affects the brain
The study involved 27,000 people aged 40 to 70. All participants underwent MRI scans, and their images were analyzed using artificial intelligence. Based on more than 1,000 markers — such as the thickness of the cerebral cortex, the state of blood vessels, and the volume of gray matter — scientists determined the "biological age" of the brain.
Those who had sleep disturbances showed signs of premature brain aging. On average, their brains looked a year older than their chronological age. Late bedtimes and short sleep durations had the greatest negative effects.
What is considered bad sleep?
Researchers assessed sleep using five criteria:
-
chronotype (time of falling asleep and waking up),
-
sleep duration,
-
insomnia,
-
snore,
-
daytime sleepiness.
Based on these scores, participants were divided into three groups: healthy, intermediate, and poor sleepers. A one-point decrease in sleep quality corresponded to approximately six months of brain aging.
Risks to cognitive health
A brain that is biologically older than its passport age has higher risks:
-
cognitive disorders,
-
dementia,
-
early deterioration of memory and attention,
-
even premature death.
Can this process be stopped?
Scientists emphasize: the good news is that healthy sleep is one of the few factors we can control. A regular regimen, 7–8 hours of sleep every night, avoiding gadgets before bed, and silence in the bedroom can actually “rejuvenate” the brain and protect it from age-related changes.
