A new study published in the September 10, 2025, issue of Neurology® reveals that chronic insomnia may accelerate memory decline and cognitive aging.
The findings suggest a 40% higher risk of developing mild cognitive impairment or dementia in people with persistent insomnia compared to those who sleep well.
Researchers followed 2,750 older adults with an average age of 70 for over five years. 16% had chronic insomnia, defined as trouble sleeping at least three times a week for three months or longer.
Those with insomnia had a 40% greater risk of developing cognitive issues—equal to aging an extra 3.5 years.
Participants underwent annual memory and thinking tests, and some had brain scans.
The scans showed that those with insomnia had more white matter hyperintensities (signs of small vessel damage) and higher levels of amyloid plaques, which are linked to Alzheimer’s disease.
Participants who reported sleeping less than usual had lower cognitive scores and more brain changes—similar to those with a genetic risk for Alzheimer’s.
On the other hand, those who slept more than usual had fewer signs of brain damage.
People carrying the APOE ε4 gene, which increases Alzheimer’s risk, showed the steepest declines in memory and thinking skills if they also had insomnia.
According to Dr. Diego Carvalho from the Mayo Clinic, treating chronic insomnia could not only improve sleep quality but also protect brain health as we age.
The study highlights that good sleep plays a key role in brain resilience and overall cognitive well-being.
One limitation is that insomnia was identified using medical records, which may miss undiagnosed or milder cases. Still, the findings add to a growing body of research linking sleep and brain health.
The study is published in Neurology.
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