Chronic insomnia may raise the risk of cognitive decline
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- Reviewed by Robert H. Shmerling, MD, Senior Faculty Editor, Harvard Health Publishing; Editorial Advisory Board Member, Harvard Health Publishing
Not only do sleepless nights make you groggy, but they also may speed up brain aging.
A study in the Oct. 7, 2025, issue of Neurology found that people with chronic insomnia — defined as being diagnosed with insomnia two times or more, at least 30 days apart — were more likely to develop cognitive issues than people without.
Researchers analyzed health data from 2,750 healthy adults (average age 70) who had no cognitive problems, about 16% of whom had chronic insomnia. Participants took annual cognitive tests to measure their processing and memory skills, and regularly self-reported their sleeping patterns. Approximately 1,000 people also underwent brain MRI about every two years to identify white matter hyperintensities, which can indicate damage to brain tissue. Another 561 participants had PET scans every 2.5 years to detect amyloid plaques, a feature associated with Alzheimer’s disease.
The researchers found that people with chronic insomnia were 40% more likely to develop mild cognitive impairment or dementia than those without. These individuals also showed faster declines on the cognitive tests.
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About the Author
Matthew Solan, Former Executive Editor, Harvard Men's Health Watch
About the Reviewer
Robert H. Shmerling, MD, Senior Faculty Editor, Harvard Health Publishing; Editorial Advisory Board Member, Harvard Health Publishing
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