The quality of your sleep may do more than just affect how you feel in the morning; it could signal how quickly your brain is getting older.
A new study from the University of California, San Francisco (UCSF) and Beth Israel Deaconess Medical Center has found that brain wave patterns recorded during sleep can help predict a person’s risk of developing dementia.
The research, published on March 19, used a machine-learning model to estimate a person’s “brain age” from sleep signals captured through an electroencephalogram (EEG).
EEG is a test that records electrical activity in the brain.
During the test, when a person’s brain age was higher than their actual age, their dementia risk went up significantly. For every 10-year gap between brain age and real age, the risk of dementia rose by nearly 40%.
WHAT DID THE BRAIN REVEAL?
The study drew on data from roughly 7,000 participants aged 40 to 94, none of whom had dementia at the beginning of the study.
They were tracked for anywhere between 3.5 and 17 years, during which about 1,000 developed the condition.
The machine-learning model analysed 13 detailed features of brain waves, picking up on patterns that standard sleep measurements tend to miss.
Amongst the significant findings were deep-sleep delta waves and sleep spindles. They are fast, short bursts of brain activity tied to memory and both play a role in brain age estimates.
Large, sudden spikes in brain activity, known as kurtosis, were linked to a lower dementia risk. These nuances were invisible to conventional sleep metrics like time spent in different sleep stages or overall sleep efficiency.
“Broad sleep metrics don’t fully capture the complex multidimensional nature of sleep physiology,” said senior author Yue Leng, MBBS, PhD, associate professor of psychiatry at the UCSF School of Medicine.
CAN DEMENTIA BE DETECTED EARLY?
Because EEG recordings can be collected non-invasively, the researchers believe brain age could one day be assessed using wearable devices outside clinical settings, offering an accessible early warning tool.
“Brain age is calculated from sleep brain waves,” said Leng. “We know that brain activity during sleep provides a measurable window into how well the brain is ageing.”
There is also hope that improving sleep health could slow brain ageing.
First author Haoqi Sun, PhD, of Beth Israel Deaconess Medical Center, noted that lifestyle changes may help, too.
“Better body management, such as lowering body mass index and increasing exercise to reduce the likelihood of apnea, may have an impact,” said Sun. “But there’s no magic pill to improve brain health.”
