September 17, 2025
Poor sleep can leave you feeling tired, testy and drained. It may also take a serious toll on the brain, shaving years off the time you stay mentally sharp.
A new study adds to growing evidence that persistent sleeplessness may set the stage for Alzheimer’s disease and other forms of dementia. It found that compared to their peers who sleep more soundly, older men and women with chronic insomnia had a 40 percent higher risk for dementia or mild cognitive impairment, a serious form of memory loss that often leads to full-blown dementia.
Those with chronic insomnia, defined as having trouble sleeping at least three days a week for three months or longer, tended to score lower on tests of memory and thinking skills than those with healthy sleep patterns. Persistent sleep troubles appeared to be especially damaging to those who carried the APOE-E4 gene variant, a known genetic risk factor for Alzheimer’s disease.
Over the long term, lack of sleep appeared to accelerate brain aging by three to four years, the researchers estimate. The findings were published in Neurology, the medical journal from the American Academy of Neurology.
“Insomnia doesn’t just affect how you feel the next day. It may also impact your brain health over time,” said study author Dr. Diego Z. Carvalho of the Mayo Clinic in Rochester, Minnesota. “We saw faster decline in thinking skills and changes in the brain that suggest chronic insomnia could be an early warning sign or even a contributor to future cognitive problems.”
For the study, the researchers tracked 2,750 older men and women for an average of 5.6 years. At the start of the study, their average age was 70, and none had serious memory problems. About 16 percent had chronic insomnia.
Participants underwent yearly tests of thinking and memory skills. Some also had brain scans to look for abnormal features known as white matter hyperintensities, caused by damage to small blood vessels, or amyloid plaques, a hallmark of Alzheimer’s disease.
Results showed that 14 percent of the people with chronic insomnia developed mild cognitive impairment or dementia, compared to only 10 percent of those who did not have insomnia. Those who got fewer hours of sleep at night also tended to score lower on the tests of memory and thinking skills and were more likely to have buildup of plaques and white matter hyperintensities in their brains, putting them at increased risk of developing Alzheimer’s disease.
“Our results suggest that insomnia may affect the brain in different ways, involving not only amyloid plaques, but also small vessels supplying blood to the brain,” Dr. Carvalho said. “This reinforces the importance of treating chronic insomnia, not just to improve sleep quality but potentially to protect brain health as we age.”
The study showed only an association between poor sleep and increased cognitive problems. But many studies in large numbers of people suggest that over time, sleeping fewer or more hours than the recommended seven to eight hours a night may play a role in dementia onset. Scientists believe that deep sleep may help to cleanse the brain, ridding the brain of toxins that can damage healthy brain cells.
Sleep problems generally increase with advancing age. While many people turn to sleeping pills, these drugs do not fully induce deep sleep and may have long-term serious side effects. There may be safer, more effective and longer lasting natural remedies for a good night’s sleep.
Consider psychological approaches like cognitive behavioral therapy, or CBT, which experts now recommend as the first-line treatment for sleep problems. CBT teaches people to challenge negative or stressful thoughts at bedtime with positive thoughts that induce relaxation. Before going to bed, think of soothing images or try meditation to help clear your head of anxious thoughts.
Avoid stimulants like coffee other caffeine-rich beverages after 3 p.m. Avoid alcohol in the hours before bedtime; alcohol may interfere with healthy sleep patterns and disrupt deep sleep.
Practice good sleep hygiene. Try to keep a consistent sleep schedule, going to bed around the same time each night. Keep the bed a place to sleep, rather than watching TV. If you can’t fall asleep within about 20 minutes, get out of bed and pursue a soothing activity like taking a bath, listening to music or reading a book.
Avoid screens around bedtime, including phones, e-readers and computer tablets. The light they emit can interfere with our natural body rhythms.
Until researchers find more effective treatments or a cure for Alzheimer’s, getting better quality sleep may be one more way to help slow the onset of dementia as the years advance.
By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Eric Schmidt, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.
Source: Diego Z. Carvalho; Bhanu Prakash Kolla; Stuart J. McCarter; et al: “Associations of Chronic Insomnia, Longitudinal Cognitive Outcomes, Amyloid-PET, and White Matter Changes in Cognitively Normal Older Adults.” Neurology, September 10, 2025
