(Press-News.org) MINNEAPOLIS — For women in their 80s, experiencing increasing sleepiness during the day over a five-year period is associated with double the risk of developing dementia during 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 daytime sleepiness causes dementia; it only shows an association.
“Sleep is essential for cognitive health, as it allows the brain to rest and rejuvenate, enhancing our ability to think clearly and remember information,” said study author Yue Leng, PhD, of the University of California, San Francisco. “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 study found that sleep problems may be intertwined with cognitive aging and may serve as an early marker or risk factor for dementia in women in their 80s.”
For the study, researchers looked at 733 female participants with an average age of 83 who did not have mild cognitive impairment or dementia at the start of the study. They were followed over five years.
During the study, 164 participants, or 22%, developed mild cognitive impairment and 93 participants, or 13%, developed dementia.
Participants wore wrist devices to track their sleep and circadian rhythm patterns for three days at the start and end of the study.
Researchers looked at the changes in nighttime sleep duration and quality, daytime napping and circadian rhythm patterns.
After five years, researchers observed large changes in sleep patterns in more than half of the participants, or 56%.
Researchers found that participants fell into three groups: stable sleep or small improvements in sleep, 44%; declining nighttime sleep, 35%; and increasing sleepiness, 21%. Declining nighttime sleep included decreases in nighttime sleep quality and duration, moderate increases in napping and worsening circadian rhythms. Increasing sleepiness included increases in both daytime and nighttime sleep duration and quality, along with worsening circadian rhythms.
Researchers then looked at how these changes were linked to the risk of developing dementia.
Of those in the stable sleep group, 25, or 8%, developed dementia. In the declining nighttime sleep group, 39, or 15%, developed dementia. In the increasing sleepiness group, 29, or 19%, developed dementia.
After adjusting for age, education and race, and health factors such as diabetes and high blood pressure, researchers found that participants in the increasing sleepiness group had double the risk of dementia compared to those in the stable sleep group. No association was found in the declining nighttime sleep group.
“We observed that sleeping, napping and circadian rhythms can change dramatically over only five years for women in their 80s,” Leng said. “This highlights the need for future studies to look at all aspects of daily sleep patterns to better understand how changes in these patterns over time can be linked to dementia risk.”
A limitation of the study was that it included primarily 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.
Discover more about dementia at BrainandLife.org, from the American Academy of Neurology. This resource also offers a magazine, podcast, and books that connect patients, caregivers and anyone interested in brain health with the most trusted information, straight from the world’s leading experts in brain health. Follow Brain & Life® on Facebook, X, and Instagram.
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.
Explore the latest in neurological disease and brain health, from the minds at the AAN at AAN.com or find us on Facebook, X, Instagram, LinkedIn, and YouTube.
END
Sleepier during the day? For some older people, it’s linked to twice the dementia risk
2025-03-19
ELSE PRESS RELEASES FROM THIS DATE:
Is increased sleepiness in our 80s tied to higher dementia risk?
2025-03-19
A study in Neurology, led by Yue Leng, PhD, and Sasha Milton, followed the sleep patterns of 733 older female participants to see if specific patterns of change were associated with a higher risk of dementia. The participants, whose average age was 83, were monitored by wrist devices that track movement and time spent asleep. They had normal cognition at the start of the study.
What They Discovered
At the end of the study, five years later, 13% had developed dementia. This included 25 participants (8%) with stable sleep patterns, 39 (15%) ...
South Africa and China establish record-breaking 12,900 km ultra-secure quantum satellite link
2025-03-19
Scientists from South Africa and China have successfully established the world’s longest intercontinental ultra-secure quantum satellite link, spanning 12,900 km. Using the Chinese quantum microsatellite Jinan-1, launched into low Earth orbit, this milestone marks the first-ever quantum satellite communication link established in the Southern Hemisphere.
In this demonstration, quantum keys were generated in real-time through Quantum Key Distribution (QKD), enabling the secure encryption of images transmitted between ground stations in China and South Africa via one-time pad encryption—considered unbreakable. The results from this pioneering ...
A rule-changer for ceramic fuel cells
2025-03-19
A joint research team from Southeast University and Shenzhen University has developed a novel function of semiconductor-ionic conductor (SIC) using a Cu-Sm co-doping ceria (SCDC). By enhancing ionic and electronic conductivity in the same time, the team is able to achieve superionic transport property and excellent fuel cell performance using the SIC electrolyte. It changes traditional pure ionic electrolyte to SIC with strong electron-ion coupling synergistic effect to obtain exceptional ionic conductivity and fuel cell performance. This study leads to a new way to develop advanced electrolytes and fuel cells in energy conversion technologies.
Ceramic ...
Good vibrations: Scientists discover a groundbreaking method for exciting phonon-polaritons
2025-03-19
NEW YORK, March 19, 2025 – Imagine a world where your phone stays cool no matter how long you use it, and it’s also equipped with tiny sensors that can identify dangerous chemicals or pollutants with unparalleled sensitivity and precision. Newly published research in the journal Nature demonstrates a new way of generating long-wave infrared and terahertz waves, which is an important step toward creating materials that can help realize these technological advances. The work, led by researchers at the Advanced Science Research Center at the CUNY Graduate Center (CUNY ASRC) paves the way for cheaper, smaller long-wave infrared light sources and more efficient device cooling.
Phonon-polaritons ...
CNIC scientists discover a type of immune cell that produces defensive "shields" in the skin
2025-03-19
A team at the Centro Nacional de Investigaciones Cardiovasculares (CNIC) led by Dr. Andrés Hidalgo has discovered a specialized population of neutrophils in the skin that produce extracellular matrix, helping to maintain the skin’s resistance and integrity. The study, published in Nature, demonstrates that the immune system not only targets pathogens, but also physically strengthens the skin to prevent them entering the body.
Neutrophils are an important type of circulating immune cell. The specialized neutrophils described ...
Science behind “Polly want a cracker” could guide future treatment design for speech disorders
2025-03-19
A new study explains how a parakeet’s brain helps it to mimic human words.
By recording for the first time the brain activity of parakeets as they made sounds, a research team at NYU Grossman School of Medicine found that their brains generate patterns seen before only in humans as they speak.
Published online March 19 in the journal Nature, the study mapped the activity of a group of nerve cells in the bird’s brain called the central nucleus of the anterior arcopallium (AAC), which is known to strongly influence the muscles in its vocal ...
Brain imaging reveals surprises about learning
2025-03-19
By revealing for the first time what happens in the brain when an animal makes a mistake, Johns Hopkins University researchers are shedding light on the holy grail of neuroscience: the mechanics of how we learn.
The team pinpointed the exact moment mice learned a new skill by observing the activity of individual neurons, confirming earlier work that suggested animals are fast learners that purposely test the boundaries of new knowledge.
The federally funded work, which upends assumptions about the speed of learning and the role of the sensory cortex, and which the researchers believe will hold true across animal ...
Scientists see the first steps of DNA unwinding
2025-03-19
For the first time, scientists have witnessed the very moment DNA begins to unravel, revealing a necessary molecular event for DNA to be the molecule that codes all life. A new study from King Abdullah University of Science and Technology (KAUST), published in Nature, captures the moment DNA begins to unwind, allowing for all the events that follow in DNA replication. This direct observation sheds light on the fundamental mechanisms that allow cells to faithfully duplicate their genetic material, a cornerstone for growth and reproduction.
Using cryo-electron microscopy and deep learning to observe the helicase ...
Earliest stages and possible new cause of stomach cancer revealed
2025-03-19
For the first time, scientists have systematically analysed somatic mutations in stomach lining tissue to unpick mutational processes, some of which can lead to cancer. The team also uncovered hints of a potential new cause of stomach cancer that needs further research.
Researchers at the Wellcome Sanger Institute, Broad Institute of MIT and Harvard, the University of Hong Kong, and their collaborators sequenced the whole genomes of normal stomach lining samples from people with and without gastric cancer.
The team ...
Unique cell shape keeps lymphatic vessels and plant leaves stable
2025-03-19
The cells that make up the walls of the finest of all lymphatic vessels have a lobate, oak leaf-like shape that makes them particularly resilient to changes in fluid volume. A similar cell shape also supports mechanical stability in plants. This has been shown by researchers from Uppsala University in a new article published in the journal Nature.
The lymphatic system consists of a network of lymph vessels that maintains the body’s fluid balance and supports the immune system. The finest of all these lymphatic vessels are called lymph capillaries. They have walls that are made up of just a single layer of lymphatic endothelial ...