Older adults who napped most days or every day had a 48% higher risk of developing dementia than those who rarely or never napped.
Falling asleep unintentionally during the day was associated with a 39% higher risk of dementia.
Researchers say the findings don't prove that napping causes dementia, but changes in sleep habits could offer an early warning sign.
Taking a nap during the day might seem like a harmless way to recharge, especially as people get older. But new research suggests that how often older adults nap — and whether they intend to fall asleep — could offer clues about their future brain health.
A study from the Johns Hopkins Bloomberg School of Public Health found that frequent and unintentional daytime napping were associated with a higher risk of developing dementia among older adults. The findings suggest that daytime sleep patterns may deserve more attention when researchers study cognitive health and dementia risk.
However, the results don't mean that taking a nap will cause dementia. Researchers say excessive daytime sleepiness could also reflect changes in the brain that occur before dementia is diagnosed.
“More frequent napping could be a marker of changes in the brain, rather than a cause of brain changes that lead to dementia,” researcher Adam Spira, Ph.D., M.A., said in a news release.
How researchers studied napping and dementia risk
The study, published in The Journals of Gerontology: Series A, examined data from 995 U.S. adults ages 65 and older who participated in the National Health and Aging Trends Study. None had possible or probable dementia when researchers began tracking their napping habits in 2013.
Researchers followed participants through 2023, examining whether they developed possible or probable dementia over the study period. They compared participants' napping frequency, whether their naps were intentional or unintentional, and how long they typically slept during the day.
The researchers also accounted for other factors that could influence dementia risk, including participants' demographic backgrounds, health conditions, nighttime sleep duration, daytime sleepiness, and risk of obstructive sleep apnea.
Dementia status was determined using a validated classification method rather than a clinical diagnosis for every participant. Because the research was observational, it could identify associations between napping and dementia but could not establish cause and effect.
What the findings mean for older adults
The results showed that participants who napped most days or every day had a 48% higher risk of developing dementia than those who rarely or never napped. Those who unintentionally fell asleep during the day had a 39% higher risk.
Nap duration also mattered. Napping for 30 minutes or less was associated with a 40% higher risk of dementia. For naps lasting longer than 30 minutes, however, the association weakened after researchers accounted for nighttime sleep characteristics.
The researchers also conducted an additional analysis that excluded dementia cases identified during the first five years of follow-up. The association between frequent napping and dementia remained, suggesting that the pattern may appear years before a diagnosis.
Still, the findings shouldn't be interpreted as a reason to avoid naps altogether. Researchers say changes in brain regions responsible for keeping people awake could contribute to increased daytime sleepiness, meaning frequent napping might be an early sign of underlying changes rather than their cause.
For consumers, the key takeaway is to pay attention to changes in sleep habits, particularly if daytime sleepiness becomes frequent or naps happen without intending to fall asleep. More research is needed to determine whether changing napping habits could actually help prevent or delay dementia.
“Monitoring napping behaviors could serve as an early and accessible marker to help identify older adults at higher risk for dementia and guide targeted interventions for dementia prevention,” researcher Kening Jiang, Ph.D., said in the release.