Nap too long, Alzheimer's?

"If you don't sleep at noon, you will collapse in the afternoon
.

" Noon nap is one of the few joys in the lives of hundreds of millions of people from middle school students to retired seniors.
Energetic at night
.

Even in a sense, the quality of naps determines the quality of life to a large extent
.

However, you know what? Always wanting to take a nap and taking a long nap may be an early warning sign of Alzheimer's disease (AD)! Recently, researchers from the University of California in the United States published a research paper entitled "Daytime napping and Alzheimer's dementia: A potential bidirectional relationship" in the journal "Alzheimer's & Dementia: The Journal of the Alzheimer's Association"
.

The study showed a two-way relationship between napping and brain aging
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Specifically, excessive daytime naps were associated with an increased risk of dementia later in life
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At the same time, having Alzheimer's disease can lead to longer naps as you age
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(Credit: Alzheimer's & Dementia: The Journal of the Alzheimer's Association) All studies on AD prior to this study had only roughly assessed participants' naps, and most were based on questionnaires
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However, the new study sought to provide a more in-depth, objective assessment of napping to determine its link to Alzheimer's disease
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To do this, they looked at data from an ongoing study called the Rush Memory and Aging Project (MAP)
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This was a prospective cohort study involving 1065 older adults with a mean age of 81 years, 812 of whom had no cognitive impairment
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During the 2-week study period, all participants wore a watch-like device on their wrists to measure sleep
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The researchers then calculated the duration and frequency of each person's naps throughout the experiment
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The study was followed up for up to 14 years
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The researchers found that for people without cognitive impairment, nap time increased by an average of 11 minutes per year with age
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However, for people with mild cognitive impairment, their nap time increased by 2 times to 24 minutes per day; patients diagnosed with AD almost tripled their nap time to 68 minutes per day! So will naps in turn affect cognition? At the start of the study, 75.
7% of the participants had no cognitive impairment, 19.
5% had mild cognitive impairment, and 4.
1% had Alzheimer's disease
.

For the next 14 years, the participants underwent an annual assessment of cognitive abilities
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Six years after the study began, 24 percent of the cognitively normal participants developed Alzheimer's disease
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The researchers compared the nap records of these "mid-sick" participants with those who remained cognitively normal and found differences in their nap habits
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The relationship between daytime naps and AD
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Panels A, B show predicted mean nap duration (A) and nap frequency (B); panels C, D show nap duration (C) or nap frequency (D) for two representative individuals
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(Credit: Alzheimer's & Dementia: The Journal of the Alzheimer's Association) When dementia was excluded, the researchers found that longer and more frequent daytime naps were key risk factors for AD in normal individuals
.

Specifically, taking at least one nap of more than an hour a day was associated with a 40% increased risk of dementia compared to people who napped less than an hour a day! In addition, with age and the development of AD symptoms, the increase in the duration and frequency of naps in patients also accelerates, which may be an important signal of cognitive impairment in old age
.

From this, the researchers describe the napping-cognition relationship as a "vicious circle
.
"
So, why is "sweet nap time" an "accomplice" of Alzheimer's disease? Another study recently published in the same journal sheds light on the causative factor of nappy sleepiness in Alzheimer's disease
.

The researchers found that excessive daytime naps are the result of the erosion of the brain's areas responsible for wakefulness by the toxic protein TAU, the accumulation of which eventually leads to Alzheimer's disease
.

(Credit: Alzheimer's & Dementia: The Journal of the Alzheimer's Association) A study of the brains of 13 deceased people with Alzheimer's disease and seven normal elderly people without the disease found that the brain was significantly different from a healthy brain.
In contrast, AD patients' brains had marked accumulation of TAU protein in the three wake-related brain regions they studied, and 75% of neurons in these regions had lost function
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TAU protein accumulation (brown spots) increased and neurons (red) decreased in brain tissue from Alzheimer's patients
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(Credit: Alzheimer's & Dementia: The Journal of the Alzheimer's Association) Consistent with the cohort study above, the authors of the study say there is indeed a reciprocal correlation between tau accumulation and daytime sleepiness
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Too much tau in the brains of AD patients can damage areas of the brain that regulate wakefulness and sleep, leading to more daytime naps
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Disrupted sleep rhythm and reduced quality of day and night will lead to more tau protein and amyloid protein clumping in the brain, further aggravating Alzheimer's disease
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Seeing this, most of my friends must have started shivering, hugging their pillows and wondering if they should close their eyes
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In fact, there is no need to be too afraid.
The nap mentioned here refers to "excessive nap", which is often an hour or more
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Numerous studies have shown that a moderate lunch break even benefits brain development and slows brain aging
.

A study published in the Journal of the American Geriatrics Society in 2016 on Chinese residents over the age of 45 divided the elderly into no nap (0 minutes), short naps (<30 minutes), and moderate naps (30 minutes).
-90 minutes) and long naps (>90 minutes)
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The participants' cognitive dimensions of orientation, attention, episodic memory, and visuospatial abilities were then assessed
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The results showed that people who took a one-hour nap after lunch performed better on psychological tests than those who took no naps, short naps and long naps
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And those who took no naps, short naps, and long naps had a decline in mental capacity that was 4-6 times that of those who took about 1 hour naps
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Those who didn't nap and those who took shorter or longer naps suffered about the same decline in mental capacity as expected with a 5-year increase in age
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It seems that the lunch break, the golden section that saves office workers a day, also has limits
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It is not possible to endure fatigue without rest, but also to be alert that sleeping for a long time may imply premature brain aging
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References[1] Li P, Gao L, Yu L, Zheng X, Ulsa MC, Yang HW, Gaba A, Yaffe K, Bennett DA, Buchman AS, Hu K, Leng Y.
Daytime napping and Alzheimer's dementia: A potential bidirectional relationship.
Alzheimers Dement.
2022 Mar 17.
doi: 10.
1002/alz.
12636.
[2] Oh J, Eser RA, Ehrenberg AJ, Morales D, Petersen C, Kudlacek J, Dunlop SR, Theofilas P, Resende EDPF, Cosme C, Alho EJL, Spina S, Walsh CM, Miller BL, Seeley WW, Bittencourt JC, Neylan TC, Heinsen H, Grinberg LT.
Profound degeneration of wake-promoting neurons in Alzheimer's disease.
Alzheimers Dement.
2019 Oct;15(10):1253 -1263.
doi: 10.
1016/j.
jalz.
2019.
06.
3916.
[3] Li J, Cacchione PZ, Hodgson N, Riegel B, Keenan BT, Scharf MT, Richards KC, Gooneratne NS.
Afternoon Napping and Cognition in Chinese Older Adults : Findings from the China Health and Retirement Longitudinal Study Baseline Assessment.
J Am Geriatr Soc.
2017 Feb;65(2):373-380.
doi: 10.
1111/jgs.
14368.
[4] Cai H, Su N, Li W, Li X, Xiao S, Sun L.
Relationship between afternoon napping and cognitive function in the ageing Chinese population.
Gen Psychiatr.
2021 Jan 25;34(1):e100361.
doi: 10.
1136/gpsych-2020-100361.
Written | Edited by Le Yi | Swagpp APP