Chronically sleepless? New study suggests it might cause your brain to age.

Persistent sleeplessness may be far worse than a passing annoyance — gradually unraveling memory and mental sharpness, according to new research.

A study recently published in Neurology, the journal of the American Academy of Neurology, identifies a troubling link: Older people who have chronic insomnia appear more likely to experience accelerated aging of the brain. These changes are revealed in both cognitive tests and imaging scans showing the altered structure of the brain.

The research involved 2,750 cognitively healthy adults with an average age of 70. The participants, who were tracked on average for 5.6 years, underwent annual testing of executive functioning, visual-spatial reasoning and other dimensions of cognition.

The data showed that 14% of those with chronic insomnia developed mild cognitive impairment or dementia, while 10% of those who did not have chronic insomnia did.

Researchers say that difference is significant in a study of this kind. Those with chronic insomnia are aging the equivalent of 3.5 additional years, a finding based on average cognitive performance and brain biomarkers expected for different age groups.

Diego Z. Carvalho, a sleep medicine specialist at the Mayo Clinic and lead author of the study, said the work supports growing evidence that suboptimal sleep, as early as in midlife, may foreshadow neurodegeneration. He noted that the study shows only an association and not causation.

“It could also be that poor sleep early on can be an indicator of cognitive decline,” Carvalho said. “It’s very hard to untangle.”

Santiago Clocchiatti-Tuozzo, a neurology resident at Yale New Haven Hospital who studies sleep and brain health, said one key finding in the study was that people with insomnia who slept fewer hours had worse outcomes, including poorer cognitive performance and more brain changes.

“If confirmed in future studies, these results could help shape strategies to preserve long-term brain health by considering not just sleep quality, but also how long people sleep,” said Clocchiatti-Tuozzo, who was not involved in the study.

Research on sleep and brain health has surged in the past decade, revealing important links between poor sleep and conditions such as dementia and Alzheimer’s. A landmark 2021 study published in JAMA Neurology found that sleeping more or less than the ideal range of seven to eight hours was connected to cognitive difficulties.

Sleeping less than six hours or more than nine hours was also tied to other health issues, including higher body mass index and increased symptoms of depression.

Karin G. Johnson, a sleep neurologist in Springfield, Massachusetts, said this type of detailed finding is fairly new for her field.

Adequate rest is crucial, Johnson said, because the brain’s process of clearing out toxins is thought to follow circadian rhythms and works best during sleep.

Johnson, an American Academy of Neurology fellow who was not involved in the study, hopes increased sleep among younger generations could lead to a healthier population in the future. She also advocates for policy changes, such as later school start times, to support better sleep habits.

“It’s important to lay that foundation of giving people enough time to sleep,” she said.