Daytime napping is common among older adults. New research from the Johns Hopkins Bloomberg School of Public Health suggests that how often, how intentionally, and how long older people nap may be linked to their risk of developing dementia.
The study , published online October 5 in The Journal of Gerontology: Medical Sciences , followed 995 U.S. Medicare beneficiaries age 65 and older who were free of dementia at the start of the study in 2013 and tracked them for up to 10 years using data from the National Health and Aging Trends Study, a nationally representative survey of older adults.
The researchers found that participants who napped frequently—defined as most days or every day—had a 48% higher risk of developing dementia compared to those who rarely or never napped, even after accounting for demographic factors, health conditions, and nighttime sleep characteristics such as sleep duration, daytime sleepiness, and a measure of obstructive sleep apnea risk.
Unintentional napping—defined as falling asleep without meaning to rather than planning a nap—was associated with a 39% higher risk of dementia. Napping for 30 minutes or less was also linked to a 40% higher risk, an association that held up after accounting for a range of potential confounders, while the association for naps longer than 30 minutes weakened once nighttime sleep factors were considered.
“More frequent napping could be a marker of changes in the brain, rather than a cause of brain changes that lead to dementia,” says Adam Spira , PhD, MA, senior author of the paper and professor in the Bloomberg School’s Department of Mental Health.
The researchers point to the likely two-way relationship between napping and dementia. Napping is a potential risk factor for dementia at the same time that degenerating brain regions that help to regulate wakefulness—which can occur early during dementia—may also lead to more frequent napping.
To help address this possibility, the team excluded dementia cases diagnosed within the first five years of follow-up and found that the associations for frequent and unintentional napping remained similar, lending support to the idea that napping patterns may meaningfully precede a dementia diagnosis rather than simply reflect it.
“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,” says Kening Jiang, PhD, a postdoctoral fellow in the Bloomberg School’s Department of Mental Health and first author of the paper.
Past research investigating the relationship between napping and cognitive decline has yielded mixed results, with some studies linking longer or more frequent naps to greater dementia risk and others finding no association or even potential benefits from short naps. The researchers note that differences in study design—including whether napping was self-reported or measured with wearable devices—and cultural attitudes toward napping across regions may help explain these inconsistent findings.
The researchers caution that the findings are observational and cannot establish that napping causes dementia. The study relied on self-reported napping habits, which can be subject to recall bias, and dementia status was determined using a validated algorithmic classification rather than clinical diagnosis.
The researchers say that longer-term studies that combine detailed, objective measures of both daytime napping and nighttime sleep are needed to clarify how napping patterns relate to dementia risk and to determine whether changing napping habits could help delay or prevent dementia onset.
“ Napping Characteristics and Incident Dementia: Results From the National Health and Aging Trends Study ” was written by Kening Jiang, Alden L. Gross, Catriona Tingsea Wu, Junxin Li, Halima Amjad, Emerson M. Wickwire, Jennifer S. Albrecht, Atul Malhotra, Chien-Yu (Irene) Tseng, Marc Kaizi-Lutu, Chunyu Liu, Christopher N. Kaufmann, and Adam P. Spira.
The study was supported in part by the National Institute on Aging (R01AG079391, K02AG095384, P30AG028740, U01AG032947, K23AG064036, 5T32AG027668-19).
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