Many people around the world take a nap at some point during the day. In hot climates taking an afternoon nap, or siesta, is a common part of the daily routine. While napping can be a healthy way to boost your mental prowess, it can also be a sign of Alzheimer’s disease.
We first reported on research linking napping to Alzheimer’s disease last year, and now there are important new findings on the topic.
According to a just-published study from Brigham and Women’s Hospital in Boston, it’s not the actual napping that’s cause for concern, but your pattern of napping.
The study involved 1,180 people from the Rush Memory and Aging Project with an average age of 81. No participant had been diagnosed with dementia at the beginning of the study, but 264 participants did suffer from mild cognitive impairment (MCI).
The participants wore an actimetry sensor– which measures gross motor activity– around a wrist for up to ten days to objectively assess their napping habits. This, the researchers say, made all of the difference because people are not likely to be careful about reporting so-called “snoozes” or “dozing off.”
The researchers defined daytime napping episodes as those occurring between 10 a.m. and 7 p.m. with continuous zero activity for ten minutes or more.
More than One Daily Nap Increases Dementia Risk
Researchers found that participants taking longer daytime naps more frequently had a higher risk of Alzheimer’s disease. For example, they found that participants who took more than one nap a day had a 30 percent increased risk of developing Alzheimer’s disease.
“(In the past) some research provided evidence that a short, planned nap may improve cognitive performance, while the others suggested that excessive self-reported daytime napping may be tied to cognitive impairment or more cognitive decline,” says Professor Peng Li, one of the study’s authors. “This study for the first time showed that longer and more frequent daytime naps were associated with increased future risk of Alzheimer’s dementia.”1
Overall, Prof. Li found that for every 30 minute increase in daily napping, there was a 20 percent increase in the risk of developing Alzheimer’s disease.2
Prof. Li presented his findings at SLEEP 2020, a joint meeting (virtual this year) of the American Academy of Sleep Medicine and the Sleep Research Society.
The new study begs the question, why is taking longer, more frequent naps linked to Alzheimer’s disease?
Napping is Related to Neuron Destruction
As we reported last year, researchers at the University of California San Francisco pointed to changes in the brain during the early stages of Alzheimer’s disease in which the disease attacks brain areas that are responsible for keeping us awake during the day.
The California scientists say that as tau, a type of protein, collects in the brain in the early stages of Alzheimer’s disease, it destroys the neurons supposed to keep us alert.
Under normal circumstances, tau is configured to attach to microtubules in the brain which supply nutrients to neurons. As Alzheimer’s progresses, the tau detaches from the microtubles and forms the twisted tangles that damage neurons.
“Our work shows definitive evidence that the brain areas promoting wakefulness degenerate due to accumulation of tau — not amyloid protein (a sticky protein that also can accumulate in the brain) — from the very earliest stages of the disease,” says researcher Lea T. Grinberg.
Prof. Grinberg and her team examined autopsies that compared the brains of people who died having normal cognitive function to folks who had Alzheimer’s.
They found tau buildup in three brain centers involved in wakefulness – what are called the locus coeruleous, the lateral hypothalamic areas and the tuberomammillary nucleus – in the brains of people with Alzheimer’s. Similar buildups were not present in healthy brains.3 What’s more, in the dementia victims these areas had lost up to 75 percent of their neurons!
“It’s remarkable because it’s not just a single brain nucleus that’s degenerating, but the whole wakefulness-promoting network,” says researcher Jun Oh. “Crucially this means that the brain has no way to compensate because all of these functionally related cell types are being destroyed at the same time.”
They published their findings in the journal Alzheimer’s and Dementia in August 2019.
Watch for Chronic Daytime Sleepiness
These remarkable findings provide a never-seen-before biological explanation for the Alzheimer’s form of dementia. As a result, chronic daytime sleepiness could serve as an important new early warning indicator of Alzheimer’s disease. If you or a loved one is napping more than usual, watch closely for memory lapses or signs of cognitive decline.
As I always say, it’s never too soon to start living an anti-Alzheimer’s lifestyle. Because by the time you may see a sign of early Alzheimer’s – like excessive napping – damage to your brain may already be taking place.
Enjoy a diet high in fresh fruits, leafy green vegetables, extra virgin olive oils and coconut oils. I also recommend supplementing with a good omega-3 in lieu of eating salmon or other cold-water fish that may be contaminated with environmental toxins. And, of course, exercise daily. These are some of your best bets for dodging memory-robbing conditions as you age.