March 30, 2022
Older men and women who take long or frequent daytime naps are at increased risk of developing Alzheimer’s disease. And increased napping frequency and time becomes more common in people with early Alzheimer’s disease
Those are the findings from a recent study that tracked more than 1,400 seniors for up to 14 years. The increased frequency and duration of napping was independent of how well someone slept at night, and suggests that Alzheimer’s may affect parts of the brain that affect our sleep and wake cycles.
“We found the association between excessive daytime napping and dementia remained after adjusting for nighttime quantity and quality of sleep,” said study author Dr. Yue Leng, of the University of California, San Francisco, Department of Psychiatry and Behavioral Sciences. Napping and Alzheimer’s disease “seem to be driving each other’s changes in a bi-directional way,” Dr. Leng added. The findings were published in the journal Alzheimer’s and Dementia.
For the study, researchers at UC San Francisco and Harvard Medical School looked at data from 1,401 older men and women who were part of an ongoing study at the Rush Alzheimer’s Disease Center in Chicago. Their average age was 81.
Every year, the participants wore a watch-like activity monitor that tracked their movement throughout the day for up to 14 days. Periods of extended inactivity from 9 in the morning until 7 at night were regarded as a nap.
Participants also underwent annual tests of memory and thinking skills. At the start of the study period, about three-fourths of the participants were free of memory problems or symptoms of Alzheimer’s disease. About 20 percent had mild cognitive impairment, a brain disorder that sometimes precedes Alzheimer’s, and 4 percent had a diagnosis of Alzheimer’s.
With increasing age, all the seniors tended to take more naps — an average of an extra 11 minutes a day each year for those without cognitive problems. But those with mild cognitive impairment napped an extra 24 minutes a day each year, and those with Alzheimer’s napped an extra 68 minutes a day each year.
Study participants who napped more than an hour a day were at 40 percent higher risk of developing Alzheimer’s disease compared to those who napped less than an hour a day. And those who took a daily nap were 40 percent more likely to develop Alzheimer’s than those who napped less frequently.
Daytime naps are common in older men and women, and in some cultures, napping is normal and happens daily. And taking naps doesn’t mean that you will develop Alzheimer’s disease. Indeed, naps have been tied to improvements in mood, alertness and performance on cognitive tasks.
Furthermore, the study’s methods had some shortcomings. People who were inactive during the day, for example, may have been watching TV rather than taking a nap. In addition, some people may have removed their activity trackers and forgot to put them back on.
But the findings add to growing evidence that Alzheimer’s disease and sleep are closely linked. Earlier studies have shown, for example, that aging men and women who said they often felt very sleepy during the day were nearly three times more likely than those who were not sleepy to have brain changes typical of Alzheimer’s disease.
Diet, exercise and engagement in cognitively stimulating activities have increasingly been recognized as important potential targets for Alzheimer’s disease prevention. Sleep is increasingly being recognized as playing an important role in Alzheimer’s disease.
If you didn’t used to take naps and you notice you’re starting to get more sleepy in the day, the authors of the current study suggest, it might be a signal of declining cognitive health. Or if people start taking more naps than usual, or napping at different times of the day than they used to, it may be a sign of a brain problem. But the results of this and other studies suggest that treating sleep issues, and promoting sound sleep, could play a role in delaying the onset of Alzheimer’s disease.
By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Marc Flajolet, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.
Source: Peng Li, Lei Gao, Lei Yu, et al: “Daytime napping and Alzheimer’s dementia: A potential bidirectional relationship.” Alzheimer’s and Dementia: Journal of the Alzheimer’s Association. March 17, 2022