MINNEAPOLIS — After a mild stroke or transient ischemic attack (TIA), people who spend more time in bed sleeping or trying to sleep may be more likely to have lower scores on tests of thinking and memory skills and changes in their brains that can lead to dementia or second strokes, according to a study published on May 28, 2025, online in Neurology® , the medical journal of the American Academy of Neurology .
Spending longer in bed—when some of that time can be not sleeping due to difficulty falling asleep, fragmented sleep, poor quality sleep or other problems—can be a sign of a sleep disorder. The study found that both people with longer in-bed times and with longer sleep durations were more likely to have these brain changes.
The study does not prove that these sleep issues cause these brain changes and thinking problems; it only shows an association.
"These results show that disturbed sleep may be a marker of adverse brain health, even for people with mild strokes or TIAs," said study author Joanna M. Wardlaw, MD, of the University of Edinburgh in the United Kingdom. "While many people know that a lack of sleep can lead to health issues, less is known about the effects of sleeping longer at night or spending a long time in bed trying to make up for having trouble sleeping—whether people are doing this consciously or not."
The study involved 422 people from Edinburgh and Hong Kong with an average age of 66 who had a mild stroke or a TIA, which is also called a "mini stroke." Within one to three months after the stroke, all participants had brain scans, filled out sleep questionnaires and took cognitive tests.
The participants had an average score of one point on a test where scores of one to four indicate a mild stroke.
People who spent a longer time in bed were more likely to have signs of damage to small blood vessels in the brain, including a greater volume of white matter hyperintensities, or areas in the white matter of the brain where brain tissue has been damaged. They were also more likely to have slightly lower scores on the test of thinking and memory skills.
People who had longer sleep duration were more likely to have small areas of microhemorrhages, or microbleeds, in the brain.
"More research is needed to confirm these findings and also to look at whether prolonged sleep has negative effects on people who have never had a stroke or TIA," Wardlaw said. "Of course, research is also needed on whether improving people's sleep patterns after stroke could ward off some of these possible detrimental effects."
The study was a snapshot in time—it did not follow participants to see changes over time, and researchers did not look at participants' sleep quality before they had strokes.
The study was supported by the UK Dementia Research Institute at the University of Edinburgh.
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The American Academy of Neurology is the leading voice in brain health. As the world's largest association of neurologists and neuroscience professionals with more than 40,000 members, the AAN provides access to the latest news, science and research affecting neurology for patients, caregivers, physicians and professionals alike. The AAN's mission is to enhance member career fulfillment and promote brain health for all. A neurologist is a doctor who specializes in the diagnosis, care and treatment of brain, spinal cord and nervous system diseases such as Alzheimer's disease, stroke, concussion, epilepsy, Parkinson's disease, multiple sclerosis, headache and migraine.
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