According to Experts Club, American researchers have found a link between frequent daytime napping and an increased risk of developing dementia in people aged 65 and older. According to a study by the Johns Hopkins Bloomberg School of Public Health, people who napped almost every day had a 48% higher relative risk of developing dementia compared to those who rarely napped.
The study’s findings were published in the scientific journal The Journals of Gerontology: Series A. The final version of the article was published on October 5, 2026, and on October 13, the university released a separate press release announcing the results.
The study included 995 Americans aged 65 and older who were covered by Medicare. At the start of the study in 2013, none of the participants showed signs of probable or possible dementia according to the classification used by the researchers.
The researchers followed the participants for up to ten years, using data from the National Health and Aging Trends Study (NHATS), a nationwide study on aging. They analyzed not only the duration of nighttime sleep but also the frequency of daytime naps, their duration, and the circumstances under which participants fell asleep.
The researchers paid particular attention to the difference between planned daytime naps and instances when a person fell asleep involuntarily, such as while watching TV, reading, or relaxing in a chair.
According to the results of the statistical analysis, frequent daytime napping was associated with a 48% increase in the relative risk of dementia, while unplanned falling asleep was associated with a 39% increase.
In their analysis, the researchers accounted for age, gender, education, the presence of chronic diseases, body mass index, symptoms of depression and anxiety, as well as characteristics of nighttime sleep and the risk of obstructive sleep apnea.
The association remained significant even after adjusting for these factors, suggesting a potential independent role of daytime napping patterns as an indicator of risk for cognitive impairment.
The researchers also found that daytime naps lasting up to 30 minutes were associated with a 40% increase in the relative risk of dementia. At the same time, for naps lasting more than 30 minutes, the statistical association weakened after accounting for characteristics of nighttime sleep.
However, irregular or intentionally scheduled daytime naps did not show a statistically significant increase in risk after adjusting for all major factors.
Overall, during the follow-up period, 417 participants—or 41.9% of the sample—showed signs of possible or probable dementia. Among people who did not nap during the day, this outcome was observed in 37.8%, and among those who regularly napped during the day, in 51.1%. However, the duration of follow-up varied across the different groups, so these percentages should not be interpreted as a direct predictor of individual risk.
In addition to dementia, the researchers found a link between frequent daytime napping and subsequent deterioration in memory and certain executive brain functions, particularly the ability to plan and control complex actions.
However, the researchers emphasize that the results do not prove a cause-and-effect relationship between daytime napping and dementia.
“More frequent daytime napping may be a sign of changes in the brain, rather than the cause of the changes that lead to dementia,” noted the study’s senior author, Adam Spira, a professor in the Department of Mental Health at Johns Hopkins University.
According to the researchers, neurodegenerative processes can begin long before the onset of clinical symptoms of dementia. Among the first areas to change may be those parts of the brain that regulate wakefulness and sleep. As a result, a person may fall asleep more often during the day even before a diagnosis is made.
To test this hypothesis, the researchers conducted an additional analysis, excluding cases of dementia identified during the first five years of follow-up. The association between frequent daytime napping and the subsequent development of dementia persisted. For unplanned sleep episodes, the direction of the association also remained similar, although the statistical uncertainty of the result increased.
The study’s first author, Kenin Jiang, noted that monitoring changes in daytime sleep could be a relatively simple way to identify people at increased risk of dementia early on.
Researchers believe that doctors should pay attention not only to patients’ complaints about nighttime sleep but also to an increase in the frequency of daytime sleepiness, especially if such changes occur for no apparent reason.
At the same time, the authors caution against drawing hasty practical conclusions. The study was observational in nature: the researchers did not alter the participants’ sleep patterns and did not test whether avoiding daytime naps could prevent dementia.
Furthermore, information about daytime napping was collected primarily from the participants themselves, and signs of dementia were identified using a validated algorithm rather than through clinical diagnosis of each individual case.
Therefore, the results do not mean that a short daytime nap is inherently harmful to the brain or that it should be avoided. Instead, new or increasingly frequent episodes of involuntary sleepiness in older adults may be a reason to discuss their health, the quality of their nighttime sleep, and possible cognitive changes with a doctor.
To definitively establish a causal link, additional long-term studies are needed that objectively measure sleep using specialized devices.
Johns Hopkins University, founded in 1876 in Baltimore, is one of the leading research universities in the United States. Its Johns Hopkins Bloomberg School of Public Health, founded in 1916, specializes in epidemiology, disease prevention, mental health, population aging, and the study of risk factors for chronic diseases. The study on daytime napping and dementia was conducted with partial funding from the U.S. National Institute on Aging.
Sources: Johns Hopkins Bloomberg School of Public Health, press release dated October 13, 2026; original research article in The Journals of Gerontology: Series A, DOI: 10.1093/gerona/glag208.
