Summary:
A 10-year study tracking nearly 1,000 Medicare beneficiaries found that older adults who nap most days or every day face a 48% higher risk of developing dementia compared to non-nappers. Unplanned, unintentional naps and brief naps under 30 minutes also correlated with increased dementia risk, suggesting daytime sleep patterns may act as early behavioral warning signs of neurodegeneration.
Key Facts:
- 48% Elevated Dementia Risk: Older adults who napped frequently (most days or daily) had a 48% higher risk of developing incident dementia compared to those who rarely or never napped, independent of nighttime sleep metrics.
- Intentionality Matters: Unintentional napping, falling asleep unexpectedly during the day, was tied to a 39% increased risk, while naps of 30 minutes or less were associated with a 40% higher risk.
- Precedes Diagnosis by Years: The relationship remained consistent even after researchers excluded participants diagnosed within the first five years of follow-up, indicating napping changes emerge years before clinical cognitive impairment.
Source: Johns Hopkins Bloomberg School of Public Health
Daytime napping is often viewed as a harmless, restorative ritual for aging adults. However, a decade-long study from the Johns Hopkins Bloomberg School of Public Health suggests that how often, how long, and how intentionally older adults nap could offer crucial prognostic clues regarding their cognitive trajectory.
Publishing in The Journal of Gerontology: Medical Sciences, researchers evaluated longitudinal data from 995 Medicare beneficiaries aged 65 and older enrolled in the National Health and Aging Trends Study (NHATS). All participants were cognitively intact at baseline in 2013 and were tracked over a 10-year observation window.
The findings demonstrate a pronounced link between daytime sleep patterns and subsequent cognitive decline: older adults who napped on most days or every day had a 48% greater risk of developing dementia compared to peers who rarely or never took naps.
Unpacking the Details: Frequency, Intent, and Duration
The research team evaluated several specific dimensions of daytime sleep, distinguishing between planned rest and involuntary nodding off, as well as tracking nap duration:
- Frequent Napping: Individuals napping on most days or daily experienced a 48% higher risk of dementia, even after controlling for demographic variables, existing health conditions, nighttime sleep duration, daytime sleepiness, and obstructive sleep apnea risk.
- Unintentional Napping: Falling asleep without intending to do so was associated with a 39% higher risk of dementia.
- Short Naps: Napping for 30 minutes or less was associated with a 40% increased risk after adjusting for confounders, whereas the link between naps longer than 30 minutes and dementia diminished after adjusting for nighttime sleep quality.
Importantly, the researchers conducted sensitivity analyses to determine whether napping was merely an immediate byproduct of late-stage undiagnosed disease. When they removed participants who received a dementia classification during the first five years of the study, the associations for frequent and unintentional napping held steady. This indicates that shifts in daytime sleep behaviors may precede formal diagnosis by half a decade or more.
A Bidirectional Relationship: Marker, Not Cause
The authors emphasize that the study does not demonstrate that taking naps causes dementia. Instead, daytime sleepiness and neurodegeneration likely share a complex, bidirectional biological connection.
“More frequent napping could be a marker of changes in the brain, rather than a cause of brain changes that lead to dementia,” said senior author Adam Spira, PhD, MA, professor in the Bloomberg School’s Department of Mental Health.
In the earliest stages of dementia, pathology can quietly damage subcortical regions responsible for wakefulness regulation and circadian rhythm synchronization. When these wake-promoting neural networks degrade, older adults may struggle to remain awake during the day, triggering frequent, unplanned episodes of daytime sleep. At the same time, fragmented circadian rhythms can worsen nighttime sleep architecture, potentially accelerating neurotoxic clearance deficits.
“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,” explained lead author Kening Jiang, PhD, a postdoctoral fellow in the Bloomberg School’s Department of Mental Health.
Resolving Conflicting Evidence
Prior scientific studies on napping and cognition have generated contradictory conclusions, with some investigations suggesting that brief “power naps” enhance working memory, while others find elevated dementia risks. The Johns Hopkins team notes that differences in study methodology, such as relying on self-reported questionnaires versus objective wrist-worn actigraphy, as well as regional and cultural norms surrounding daytime rest, likely account for these discrepancies.
Because this study relied on self-reported napping habits and algorithmic classification of dementia, the researchers caution that clinical diagnostic trials and objective wearable sleep monitoring are needed to confirm these relationships.
Future investigations will aim to explore whether behavioral interventions designed to stabilize wakefulness and consolidate nighttime sleep can help delay the onset of cognitive decline in older adults.
Funding: The study was supported in part by the National Institute on Aging (R01AG079391, K02AG095384, P30AG028740, U01AG032947, K23AG064036, 5T32AG027668-19).
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- Journal paper reviewed in full.
- Additional context added by our staff.
About this dementia Research:
- Media Contact: Saznin Mehta
- Source: Johns Hopkins University
- Image Credit: Image credited to Neuroscience News
- Original Research is Open Access: Journal of Gerontology: Medical Sciences (Oct 1, 2026). “Napping characteristics and incident dementia: results from the National Health and Aging Trends Study.” Authors: Kening Jiang, PhD; Alden L. Gross, PhD; Catriona Tingsea Wu; Junxin Li, PhD; Halima Amjad, MD, PhD; Emerson M. Wickwire, PhD; Jennifer S. Albrecht, PhD; Atul Malhotra, MD; Chien-Yu (Irene) Tseng, PharmD; Marc Kaizi-Lutu, BA; Chunyu Liu, MS; Christopher N. Kaufmann, PhD; and Adam P. Spira, PhD.
- DOI: 10.1093/gerona/glag208
Abstract
Napping characteristics and incident dementia: results from the National Health and Aging Trends Study
Background
Whether daytime napping may be a risk factor for dementia, in addition to nighttime sleep disturbances, remains unclear. This study investigated longitudinal associations of napping characteristics with incident dementia among U.S. older adults.
Methods
Data came from the National Health and Aging Trends Study (NHATS). Napping characteristics were self-reported in a sleep module at round 3 (2013), including (1) frequency (non-napper, infrequent, frequent); (2) intention (non-napper, intentional, unintentional); (3) duration (non-napper, ≤30 minutes, >30 minutes). Dementia classification was established at each round using a validated algorithm, and possible/probable dementia served as our outcome.
We included 995 participants free of possible/probable dementia at round 3 who were followed up to round 13 (2023). Discrete-time complementary log-log models were used for hazard ratio (HR) of incident possible/probable dementia associated with napping characteristics, adjusting for demographic, health, and sleep variables (duration, daytime sleepiness, and obstructive sleep apnea risk).
Results
When compared to non-nappers, frequent nappers had 1.48 times the hazard of developing incident possible/probable dementia (95% confidence interval [CI]: 1.14, 1.94). Unintentional napping was associated with incident possible/probable dementia (HR = 1.39, 95% CI: 1.06, 1.81). No associations were found for infrequent or intentional napping. Napping ≤30 minutes was associated with possible/probable dementia (HR = 1.40, 95% CI: 1.06, 1.85), but the association of napping >30 minutes was attenuated with additional adjustment for sleep variables (HR = 1.28, 95% CI: 0.96, 1.69).
Conclusions
Daytime napping may be a modifiable risk factor for dementia if supported by further evidence. Future studies with detailed napping characteristics and longer follow-up are needed.