Study Links Frequent Daytime Naps to Higher Dementia Risk

Frequent daytime napping may signal a higher risk of dementia in older adults, according to research published in The Journals of Gerontology: Medical Sciences. Researchers from the Johns Hopkins Bloomberg School of Public Health followed nearly 1,000 adults aged 65 and older for a decade to examine how daytime rest patterns relate to long-term brain health.

Participants who napped most days or every day had a 48% higher risk of developing dementia than those who rarely or never napped, the study found. Older adults who unintentionally fell asleep during the day had a 39% higher risk, while naps lasting 30 minutes or less were associated with a 40% increase in risk after adjustments for other health factors.

The association between naps longer than 30 minutes and dementia was less pronounced after researchers accounted for nighttime sleep patterns. The findings also remained after adjustments for nighttime sleep duration, daytime drowsiness and indicators of sleep apnea.

Adam Spira, Ph.D., a professor at the Bloomberg School, and postdoctoral fellow Kening Jiang, Ph.D., said the research examined several characteristics of daytime rest rather than focusing exclusively on nap duration.

"Our study highlights the importance of looking beyond just how long people nap and considering other napping characteristics, such as how frequently they nap and whether their naps are intentional," the study authors told Fox News Digital.

The researchers said their findings provide evidence of an association between daytime sleep habits and dementia risk over time. However, the study does not establish that napping itself causes dementia.

Spira and Jiang also explained that daytime rest and nighttime sleep can influence each other, potentially complicating the relationship between sleep habits and brain health.

"Nighttime sleep and daytime napping are closely related," Spira and Jiang said.

They noted that daytime naps may compensate for inadequate nighttime rest but could also reduce the body's drive to sleep at night. Disrupted nighttime sleep is another potential risk factor for dementia, according to the researchers.

The team also investigated whether changes in napping might emerge before dementia becomes clinically apparent. Researchers repeated their analysis after excluding participants who developed dementia during the first five years of follow-up.

The association between frequent, unintentional naps and dementia remained strong in that analysis. The findings suggest that altered daytime sleep patterns may precede a formal diagnosis by several years.

The researchers said brain regions responsible for regulating wakefulness can deteriorate during the early stages of dementia, potentially contributing to increased daytime fatigue. This raises the possibility that frequent or unintentional naps reflect underlying changes rather than directly causing them.

Spira and Jiang emphasized that the observational design limits the conclusions researchers can draw because participants were not assigned to change their sleeping habits.

"We did not directly intervene on participants’ napping behaviors to examine whether changing these behaviors would affect their dementia risk," Spira and Jiang told Fox News Digital.

The researchers said the findings identify daytime napping patterns as a potential indicator of future dementia risk, while leaving unanswered whether modifying those patterns could affect the likelihood of developing the condition.