An afternoon nap is one of the small comforts of getting older, but these findings may make many think twice about their next nap. A new study that tracked nearly 1,000 older Americans for up to a decade found that people who napped most days or every day had a 48% higher risk of developing dementia than people who rarely or never napped.
Nodding off by accident carried its own warning sign. Older adults who said at least some of their naps happened without meaning to had a 39% higher dementia risk, while people who only took planned naps showed no clear link once their health and nighttime sleep were taken into account. By the end of the study, about half of the frequent nappers had developed signs of dementia, compared with roughly 38% of people who skipped naps.
Some 6.9 million older Americans are estimated to live with dementia, a number expected to roughly double by 2060. Poor nighttime sleep is increasingly recognized as a risk factor, but research on daytime napping has produced mixed results, with some studies finding harm and others finding none or even a small benefit from short naps. This study cannot prove that napping causes dementia, since it observed people’s habits rather than changing them. Still, it puts frequent and unplanned napping on the radar as a possible early clue.
A 10-year study of napping and dementia risk in older adults
Researchers led by Johns Hopkins University drew on the National Health and Aging Trends Study, a national survey of Medicare recipients age 65 and older who have been interviewed in person every year since 2011. In 2013, 1,623 of those participants were picked to answer an extra set of sleep questions, including several about napping. After setting aside people with missing information or signs of dementia at the start, the team followed 995 participants through 2023. About 60% were women, roughly 78% were non-Hispanic white, and about 16% were Black. Statistical weights were applied so the results would better reflect older Americans as a whole.
No one received a formal dementia exam from a doctor as part of the study. Instead, the survey used a validated scoring system that combines three sources: whether a participant or family member reported a dementia diagnosis, a short questionnaire answered by a relative or caregiver, and simple tests of memory, orientation (knowing the date and who the president is), and planning skills measured by drawing a clock. People who scored poorly in one of those three thinking areas were classified as having “possible” dementia, and stronger evidence earned a “probable” label. Researchers counted both. Over a median follow-up of five years, 417 of the 995 participants, about 42%, developed possible or probable dementia.
Three ways researchers measured napping habits
Instead of a simple yes-or-no question, the team looked at napping three ways. Frequency came first: people who napped “never” or “rarely” in the past month counted as non-nappers, “some days” made someone an infrequent napper, and “most days” or “every day” made someone a frequent napper. Intention came next. Nappers who said their naps were planned were labeled intentional nappers, while those who fell asleep without meaning to, or reported a mix of planned and unplanned naps, were labeled unintentional nappers. Length was the third measure, with naps sorted into 30 minutes or less and longer than 30 minutes.
Intention matters because a scheduled rest after lunch can be a lifelong habit, while dozing off unexpectedly may point to sleepiness driven by poor nighttime sleep or other health problems. Unintentional nappers in this study fit that second pattern. Compared with non-nappers, they had more chronic health conditions, higher body weight, more symptoms of depression, a higher risk of sleep apnea (a disorder in which breathing repeatedly stops and starts during sleep), and more frequent daytime sleepiness.
Frequent and accidental napping tied to higher dementia risk
Raw numbers showed a clear gap. About 51% of frequent nappers developed possible or probable dementia, compared with 42% of infrequent nappers and 38% of non-nappers. Frequent nappers also tended to carry more weight, have more health conditions, and report more depressive symptoms, so researchers adjusted for those differences along with age, education, smoking, anxiety, nighttime sleep length, daytime sleepiness, and sleep apnea risk. After all those adjustments, frequent nappers still had a 48% higher risk than non-nappers. Infrequent napping showed no clear link.
Unintentional napping held up through every round of adjustment, ending with a 39% higher risk. Planned napping looked risky at first, but that connection faded once health and sleep factors were added to the analysis.
Nap length produced a mixed result. Naps of 30 minutes or less were linked to a 40% higher dementia risk after all adjustments. Naps longer than 30 minutes showed a similar link at first, but it weakened once nighttime sleep, daytime sleepiness, and sleep apnea risk were factored in. In the authors’ view, a possible explanation is that longer naps may be more about making up for bad nights, so their link to dementia may really reflect poor nighttime sleep.
When researchers looked at individual thinking skills, memory showed the most consistent pattern. Frequent napping, unintentional napping, and short naps were all tied to a higher risk of developing memory problems. Napping showed no link to orientation problems, and results for the clock-drawing planning test were inconsistent.
Source : https://studyfinds.com/napping-most-days-higher-dementia-risk/