Frequent Daytime Naps Linked to Higher Dementia Risk in New Study

Frequent daytime napping among older adults may be linked to a higher risk of developing dementia, according to a new study published in The Journal of Gerontology: Medical Sciences. The research found that people who nap on most days or every day face a notably higher risk than those who rarely or never nap.

Researchers from the Johns Hopkins Bloomberg School of Public Health carried out the study. They tracked nearly 1,000 adults aged 65 and older who showed no signs of memory or thinking problems when the study began in 2013.

A decade later, the researchers found that daytime rest habits — how often people nap, how long they sleep and whether they fall asleep by accident — are linked to long-term brain health. Nighttime sleep quality or duration alone, they say, does not capture the full picture.

The study found that participants who napped frequently, defined as most days or every day, had a 48 percent higher risk of developing dementia compared to those who rarely or never napped.

Whether the naps were intentional also appeared to matter. Seniors who fell asleep unintentionally had a 39 percent higher risk, while shorter naps were also linked to poorer outcomes.

Napping for 30 minutes or less was linked to a 40 percent increased risk of dementia, even after researchers adjusted for other health factors. For naps longer than 30 minutes, the association was less pronounced after researchers accounted for nighttime sleep patterns.

The research team stressed that looking at daytime napping habits gives a much clearer picture of overall health than looking at nighttime sleep alone. Study authors Adam Spira, a professor at the Bloomberg School, and postdoctoral fellow Kening Jiang said it is important to consider how frequently people nap and whether their naps are intentional.

They said the study provides important longitudinal evidence that frequent and unintentional daytime napping was associated with a higher risk of developing dementia among older adults. The findings held even after accounting for nighttime sleep length, daytime drowsiness and indicators of sleep apnea.

The researchers pointed out, however, that daytime resting does not necessarily cause brain changes. Rather, changing nap habits could be an early warning sign of underlying changes in the brain.

Brain regions that help regulate wakefulness can start to break down in the early stages of dementia, leading to more frequent daytime fatigue, they noted. Daytime napping may also compensate for poor nighttime sleep, but it can reduce the drive to sleep at night and contribute to nighttime sleep disturbances, another potential risk factor.

To double-check the result, the team re-analysed the data after removing anyone who developed dementia during the first five years. The link between frequent, accidental naps and dementia remained just as strong, suggesting that changes in napping habits can show up years before a formal diagnosis.

The researchers emphasized that this was an observational study with limitations. They did not directly intervene in participants’ napping behaviours to examine whether changing those behaviours would affect dementia risk. Still, they say daytime napping patterns in older adults may be worth monitoring, particularly when naps become frequent or happen unintentionally.