Summary:
A 10-year study of nearly 1,000 Medicare beneficiaries found that older adults who nap most days or every day had a substantially higher risk of developing dementia than those who rarely or never nap. The research also linked unplanned daytime dozing and short naps (30 minutes or less) with elevated dementia risk, suggesting daytime sleep habits may be early behavioral indicators of underlying neurodegeneration.
Key Facts:
- 48% higher dementia risk: Participants who reported napping most days or daily faced a 48% greater risk of developing dementia versus non-nappers, after accounting for nighttime sleep measures and other health factors.
- Unintentional naps matter: Falling asleep unintentionally during the day was associated with a 39% increased risk of incident dementia.
- Short naps linked to risk: Naps of 30 minutes or less were tied to a 40% higher risk, while longer naps showed a weaker association after adjusting for nighttime sleep quality.
Source: Johns Hopkins Bloomberg School of Public Health
Overview: Daytime napping is commonly regarded as a harmless or even restorative habit for older adults. However, a longitudinal analysis from the Johns Hopkins Bloomberg School of Public Health shows that how often, how long, and whether naps are intentional could provide meaningful early clues about cognitive decline.
Published in The Journal of Gerontology: Medical Sciences, the study followed 995 Medicare beneficiaries aged 65 and older who were cognitively intact at the 2013 baseline and were observed through 2023 as part of the National Health and Aging Trends Study (NHATS). Researchers examined self-reported napping behavior and used an established algorithm to classify incident possible or probable dementia over the decade of follow-up.
Frequency, Intentionality, and Duration
The team analyzed three main napping characteristics: how often people napped, whether naps were planned or occurred unintentionally, and how long naps lasted. Key results included:
- Frequent napping: People who napped most days or daily had a 48% higher hazard of developing incident possible or probable dementia compared with non-nappers, even after adjusting for demographics, health conditions, nighttime sleep duration, daytime sleepiness, and risk of obstructive sleep apnea.
- Unintentional dozing: Napping that occurred without intention — falling asleep during the day unexpectedly — was associated with a 39% greater risk of dementia.
- Short naps: Individuals reporting naps of 30 minutes or less showed a 40% increased risk, while associations for naps longer than 30 minutes were reduced after controlling for sleep-related variables.
To test whether napping simply reflected undiagnosed, advanced disease, the researchers reran analyses after excluding participants who were classified with dementia in the first five years of follow-up. The associations for frequent and unintentional napping remained, indicating that changes in daytime sleep behavior can appear years before a clinical dementia diagnosis.
Interpreting the Link: Marker, Not Proven Cause
The investigators stress that these findings do not establish that napping causes dementia. Rather, daytime sleepiness and napping may be early markers of brain changes linked to neurodegenerative processes.
“More frequent napping could be a marker of changes in the brain, rather than a cause of brain changes that lead to dementia,” said Adam Spira, PhD, MA, a senior author and professor in the Bloomberg School’s Department of Mental Health.
Researchers describe biological pathways that could explain the association: early neurodegenerative changes in subcortical regions that regulate wakefulness and circadian rhythms may make it harder for older adults to stay awake during the day. This excessive daytime sleepiness can produce frequent, often unplanned naps. At the same time, disrupted circadian rhythms and fragmented nighttime sleep could impair brain processes involved in clearing metabolic waste, potentially accelerating cognitive decline.
Lead author Kening Jiang, PhD, noted that monitoring napping behavior may offer a practical, low-cost approach to identifying older adults at elevated risk for dementia and could help target preventive interventions.
Reconciling Conflicting Evidence
Previous studies on napping and cognition have reached mixed conclusions: some report cognitive benefits from brief “power naps,” while others find associations with higher dementia risk. The Johns Hopkins team points out methodological differences — for example, self-reported versus objectively measured sleep, and cultural norms around napping — that likely contribute to inconsistent findings across studies.
Because the current analysis relied on participants’ self-reports of napping and an algorithmic dementia classification, the authors call for further research using clinical diagnostic evaluations and objective sleep monitoring with wearable devices to validate and refine these results.
Future work will also examine whether interventions that stabilize daytime wakefulness and strengthen nighttime sleep could delay or reduce the risk of cognitive decline among older adults.
Funding: The study received partial support from the National Institute on Aging (grants listed in the original publication).
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- The journal paper was reviewed in full.
- Additional context was provided by staff.
About this dementia Research:
- Media Contact: Saznin Mehta
- Source: Johns Hopkins University
- Image Credit: Image credited to Neuroscience News
- Original Research (open access): Journal of Gerontology: Medical Sciences (Oct 1, 2026). Title: “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
The extent to which daytime napping represents an independent risk factor for dementia, distinct from disturbances in nighttime sleep, remains uncertain. This study examined longitudinal associations between napping patterns and incident dementia in older U.S. adults.
Methods
Researchers used NHATS data and a sleep module from round 3 (2013) to classify self-reported napping by frequency (non-napper, infrequent, frequent), intention (non-napper, intentional, unintentional), and duration (non-napper, ≤30 minutes, >30 minutes). Dementia status was determined at each round by a validated algorithm. The analysis included 995 participants without possible or probable dementia at baseline who were followed through round 13 (2023). Discrete-time complementary log-log models estimated hazard ratios for incident possible/probable dementia associated with napping characteristics, adjusting for demographic, health, and sleep-related covariates.
Results
Compared with non-nappers, frequent nappers had a 1.48-fold hazard of developing incident possible or probable dementia (95% CI: 1.14–1.94). Unintentional napping was associated with increased dementia risk (HR = 1.39, 95% CI: 1.06–1.81). Naps ≤30 minutes were associated with higher risk (HR = 1.40, 95% CI: 1.06–1.85), while associations for naps longer than 30 minutes were weakened after adjusting for sleep-related variables.
Conclusions
Daytime napping may be a modifiable risk marker for dementia pending confirmation in further studies. Additional research with detailed, objective measures of napping and longer follow-up is needed to clarify whether and how napping behavior could be used in dementia prevention strategies.