A study published October 16, 2026 in the Journals of Gerontology found that older adults who napped most days had a 48 percent higher risk of dementia than those who rarely or never napped. But the researchers who ran the study stress one point above all others: their work cannot prove that naps cause dementia. Here is what the data actually shows, and what it means for your afternoon nap.
What the Johns Hopkins Study Actually Found
The research came out of the Johns Hopkins Bloomberg School of Public Health in Baltimore. Lead researcher Kening Jiang, a postdoctoral fellow in mental health research, and senior researcher Adam Spira, a professor in the Department of Mental Health, tracked more than 990 Medicare beneficiaries aged 65 and older for up to 10 years, starting in 2013. Every participant was free of dementia when the study began.
Three findings made the headlines:
- Older adults who napped most days or every day had a 48 percent higher risk of developing dementia than those who rarely or never napped.
- Unintentional napping, meaning falling asleep during the day without planning to, was linked to a 39 percent higher risk.
- Napping for 30 minutes or less was tied to a 40 percent higher risk.
“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,” Jiang said in the news release.
That framing is deliberate. The word is marker, not cause.
The Causation Caveat: This Is the Most Important Part
The researchers warned explicitly that the study was not designed to prove a direct cause-and-effect link between daytime napping and dementia. It found an association, and associations have a direction problem.
There is likely a two-way relationship between napping and dementia. Napping could be a potential risk factor for dementia, but the onset of dementia can also damage brain regions that help regulate wakefulness, which leads to more frequent napping. In plain terms, the naps may be a symptom of brain changes already underway, not the thing causing them.
Spira put it directly: “More frequent napping could be a marker of changes in the brain, rather than a cause of brain changes that lead to dementia.”
This matters because the scarier interpretation, that your afternoon nap is damaging your brain, is not what the data supports. Excessive daytime sleepiness may be one of the earliest visible signs of changes in the brain, showing up before a diagnosis. The nap is the smoke, not the fire.
Why Unintentional Naps and Short Naps Looked Riskier
The finding that catches people off guard is the short-nap result. Conventional sleep advice says short naps are fine and long naps are the problem. This study found the opposite pattern.
The explanation sits in the word unintentional. Falling asleep without meaning to is a sign of daytime sleepiness, which is a different phenomenon from choosing to rest. People who plan a nap tend to nap on purpose, often for a set time. People who doze off in short, unplanned bursts are often fighting to stay awake, and losing. The 39 percent higher risk attached to unintentional napping is really a signal about sleepiness, not about naps as a practice.
The 40 percent figure for naps of 30 minutes or less fits the same pattern. Short, frequent, unplanned dozing is what excessive daytime sleepiness looks like in real life. It is not the same as a deliberate 20-minute rest, even if the clock says the same number.
What Other Research Says About Naps and the Brain
This is not the first study to connect napping patterns with dementia risk.
Researchers using wrist-worn activity sensors in Chicago followed older adults for years and reported in Alzheimer’s and Dementia in 2022 (Li et al.) that more frequent and longer daytime naps were associated with a higher risk of dementia, and that nap patterns changed in the years before a diagnosis.
At UC San Francisco, the Grinberg lab reported in 2019 (Oh et al.) that the brain cells that keep us awake are among the very first destroyed by Alzheimer’s disease. Tau protein damage hits wake-promoting neurons early, which is a direct biological reason why daytime sleepiness can show up before cognitive symptoms.
On the other side of the ledger, short planned naps have real, documented benefits in healthy adults. The most famous study is NASA’s cockpit nap research led by Mark Rosekind at Ames Research Center in the 1990s. Twenty-one long-haul pilots were given a planned 40-minute rest opportunity mid-flight and slept an average of 25.8 minutes. Compared with the no-rest group, the nappers showed a 34 percent improvement in performance and a 54 percent improvement in physiological alertness, with the benefits carrying through the most demanding phase of the flight.
A genetic study published in Sleep Health in 2023 (Paz, Dashti and Garfield) analyzed data from about 378,000 people in the UK Biobank and found that a genetic predisposition to regular napping was associated with slightly larger brain volume, which complicates any simple story that napping is bad for the brain.
So the evidence cuts both ways, which is exactly why the distinction between planned naps and unplanned daytime sleepiness is the whole game.
The Bottom Line: Should You Keep Napping?
Here is how to read this study without panic and without dismissing it.
A planned, intentional afternoon nap is not what this research flags. The signal sits with frequency and intent: napping most days or every day, and falling asleep without meaning to. If you have always taken a short afternoon nap and feel fine, this study gives you no reason to stop.
What deserves attention is a change. If you rarely napped and now find yourself dozing off most afternoons, or if you catch yourself falling asleep in front of the television or at the table without intending to, that change is worth mentioning to your doctor. Not because the naps are harming you, but because the sleepiness itself may be telling you something about your brain that a blood test cannot.
Keep the nap intentional, keep it earlier in the afternoon so it does not steal from nighttime sleep, and pay attention to what your daytime sleepiness is doing over time. The researchers’ message is not to fear the nap. It is to notice when the nap starts happening to you.
If your nights are the problem behind your days, start with science-backed tips for improving sleep quality naturally, and for natural strategies for sleeping better without medication. The longest-lived populations take rest seriously too, see the secrets of the world’s longest-lived people.
