So far, research aimed at determining how napping affects cognition in adults has had mixed results. Some studies seem to indicate that napping is beneficial for cognition in young adults. Others, made in older adultsOn the contrary, they suggest that taking a nap could be related to the appearance of cognitive alterations.
However, many of these studies are based solely on self-report data. However, in some cases, this methodology may not be precise enough: people with cognitive impairment, in particular, may find it difficult to provide reliable information on the length or frequency of their naps.
What’epidemiologist studying sleep and neurodegeneration in the elderly, I investigated whether changes in napping patterns could be predictors of cognitive impairment. The results I obtained with my collaborators show that it is normal for the duration of naps to increase as one ages, but that excessive lengthening could well be a sign of cognitive decline.
VIDEO : Sleep and Alzheimer’s disease could be linked (subtitled VO)
Link Between Napping and Dementia
Sleep disturbances and bumpy naps are well-known symptoms associated with mild to moderate forms of Alzheimer disease, as well as other forms of dementia in the elderly. Souvent, to measure that the maladie progresses, ces symptômes deviennent plus extrêmes: les patients parviennent de moins en moins à trouver le sommeil lorsqu’ils se couchent, sont plus susceptible de se réveiller durant la nuit, et donc plus inclins à se somnolents During the day.
To examine the link between napping and dementia, my colleagues and I studied a group of 1,401 people with an average age of 81 years. These people participated in draft Rush Memory and Aging, a longitudinal study designed to analyze cognitive decline and Alzheimer’s disease. For fourteen years, the participants wore a device, similar to a wristwatch, intended to track their mobility. Periods of prolonged inactivity were interpreted as naps.
At the start of the study, approximately 75% of patients showed no signs of cognitive decline. Among the other patients, 4% had Alzheimer’s disease and 20% had moderate cognitive impairment, which is often a harbinger of dementia risk.
Over the years, the daily length of naps has increased for all participants; however, we have seen differences between people with Alzheimer’s disease and those without. The naps of the participants who did not develop cognitive impairment lengthened by an average of 11 minutes per year.
In people diagnosed with moderate cognitive impairment, this duration more than doubled: Nap duration increased by an average of 25 minutes per year. Finally, in participants diagnosed with Alzheimer’s disease, this elongation tripled again, reaching an additional 68 minutes per year, on average.
Ultimately, we found that seniors who napped at least once a day, or slept more than an hour during the day, were 40% more likely to develop Alzheimer’s than those who didn’t. daily nap or slept more than one hour. those who took a nap that lasted no more than an hour. These results remained unchanged even after correcting for factors such as daily activities, illness, or taking medication.
The Nap and the “Alzheimer’s” Brain
Our study shows that longer naps are a normal part of aging, but only up to a point. Our colleagues from theUniversity of California in San Francisco have identified a mechanism that may explain why people with dementia take longer and more frequent naps.
They carried out the post-mortem comparison of the brains of people who died without having suffered any cognitive impairment with the brains of people affected by Alzheimer’s disease. The results revealed that in the latter, three brain regions harbored fewer nerve cells (neurons) involved in wakefulness. These neuronal changes appear to be related to presence of Tau protein aggregatesmarkers of Alzheimer’s disease that form when Tau protein, which helps stabilize healthy neurons, forms clumps that eventually impede communication between neurons.
Although our study does not demonstrate that increased napping leads to cognitive decline, it does indicate that prolonged napping is a potential sign ofaccelerated aging. Further research would determine whether monitoring nap length could help better detect the onset of cognitive decline.
This analysis was written by Yue Leng, an assistant professor of psychiatry at the University of California, San Francisco.
The original article was translated (from English) and published on the site of The conversation.
declaration of interests
● Yue Leng receives funding from the National Institute on Aging.