Daytime sleepiness may double dementia risk in elderly women

For women in the 1980s, the experience of increasing sleepiness during the day for a period of five years is associated with double the risk of developing dementia at that time, according to a study published on March 19, 2025, online in Neurology^®The Medical Journal of the American Academy of Neurology. The study does not prove that sleepiness causes dementia during the day; It only shows an association.

Sleep is essential for cognitive health, because it enables the brain to rest and rejuvenate, which improves our ability to think clearly and to remember information. However, little is known about how changes in sleep and cognition are connected over time and how these changes relate to dementia risk in the later decades of life. Our studies showed that sleeping problems can be intertwined with cognitive aging and can serve as an early marker or risk factor for dementia in women in the 80s. “

Yue Leng, PhD, Study Author, University of California, San Francisco

For the study, researchers looked at 733 female participants with an average age of 83 who had no mild cognitive impairment or dementia at the start of the study. They were followed for five years.

During the study, 164 participants, or 22%, developed mild cognitive disorders and developed 93 participants, or 13%, dementia.

Participants wore wrist devices to follow their sleeping and circadian Ritmpatronen for three days at the start and end of the study.

Researchers looked at the changes in nocturnal sleep duration and quality, nap during the day and circadian rhythm patterns.

After five years, researchers saw major changes in sleep patterns in more than half of the participants, or 56%.

Researchers discovered that participants fell into three groups: stable sleep or small improvements asleep, 44%; Falling night’s rest, 35%; And increasing sleepiness, 21%. Falling nocturnal sleep included decrease in nocturnal sleep quality and expensive, moderate increase in naps and worsening circadian rhythms. Increasing sleepiness included an increase in both day and night -time sleeping time and quality, along with deteriorating circadian rhythms.

Researchers then looked at how these changes were linked to the risk of developing dementia.

Of those in the stable sleeping group, 25 or 8%, developed dementia. 39 or 15%developed dementia in the falling nocturnal sleeping group. 29 or 19%developed dementia in the increasing sleepiness group.

After correction for age, education and race, and health factors such as diabetes and high blood pressure, researchers discovered that participants in the increasing sleepiness group had the risk of dementia compared to those in the stable sleeping group. No association was found in the decreasing nightly sleeping group.

“We have noticed that sleeping, sleeping and circadian rhythms can change dramatically for women in the 80s for only five years,” Leng said. “This emphasizes the need for future studies to look at all aspects of daily sleep patterns to better understand how changes in these patterns can be linked to dementia risk over time.”

A limitation of the research was that it mainly included white people, so the results cannot be generalized to more diverse populations.

The study was funded by the National Institutes of Health and the National Institute on Aging.