A new study revealed certain sleep habits are making people’s brains a full year older than they actually are, putting people at risk of cognitive decline and a range of other issues
People who sleep poorly are more likely to have brains older than they actually are, according to a new brain imaging study published in the journal eBioMedicine. Poor sleep has previously been linked to dementia, and this new discovery has shed light on the link between these two conditions.
Abigail Dove, researcher at the Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, said: “Our findings provide evidence that poor sleep may contribute to accelerated brain aging and point to inflammation as one of the underlying mechanisms. Since sleep is modifiable, it may be possible to prevent accelerated brain aging and perhaps even cognitive decline through healthier sleep.
“The gap between brain age and chronological age widened by about six months for every one-point decrease in healthy sleep score. People with poor sleep had brains that appeared, on average, one year older than their actual age.”
The study followed 27,500 middle-aged and older people from the UK Biobank who had MRIs of their brains. The scientists then used machine learning to estimate the age of each person’s brain on a biological level, based on its health, and compared it to their chronological age, which is based on the date of birth. The difference between these two numbers was dubbed the brain age gap.
The participants were also assigned a sleep quality score based on five different factors:
- Sleep duration per day, including naps
- Insomnia
- Snoring
- Daytime sleepiness
- Chronotype – whether they described themselves as a morning or night person
People who were early risers, getting between seven to eight hours of sleep, and with no reports of insomnia, snoring, or daytime sleepiness scored five points. For the study, the ‘healthy’ sleep group consisted of those scoring four or more points, intermediate was two to three points, and poor scored one point or less.
Both intermediate and poor sleep groups had “significantly higher” brain age gap than healthy sleepers. The brain’s age accelerated around six months for every single point lost to bad sleep habits.
On average, people with an intermediary sleep pattern had a brain age around seven months older than their actual age. Those in the poor sleep group had a brain age almost a full year older than their chronological age.
The study concluded: “Having an older brain age is an early indicator of a departure from optimal brain health. Our findings relating poor sleep to older brain age support the notion that poor sleep may be a risk factor for the development of dementia.
“Future studies are necessary to determine whether improving sleep characteristics can prolong brain and cognitive health.”
The study also found that those with intermediary and poor sleep patterns were more likely to be older and male, with a higher BMI and prevalent cardiometabolic diseases. They were also less likely to have a college degree and a healthy lifestyle.
As for why sleep affects brain age, some theories noted by News Medical claim that the brain’s waste clearance system, which is mainly active during sleep, is negatively affected by poor sleep. Or that poor sleep affects cardiovascular health, which in turn has a negative impact on the brain.