Comment by random_ind_dude | Hacker News Reader

Comment by random_ind_dude | Hacker News Reader

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random_ind_dude

What makes you think that the scientists didn't consider the possibility that poor sleep at night was the actual causative factor driving the progression of mild cognitive impairment (MCI) and Alzheimer's dementia?

From the paper:

>Nighttime sleep disturbances are known risk factors for developing cognitive impairment or dementia. We found that the association between excessive daytime napping and incident Alzheimer's dementia remained with similar effect sizes after adjustment of covariates for nighttime sleep quantity and quality including sleep duration, sleep fragmentation, and WASO, implying a role of daytime napping independent from changes in these nighttime sleep-related characteristics. We further note that we did not observe direct associations between these nighttime sleep measures and incident Alzheimer's dementia. Therefore, it is unlikely that the increased duration and frequency of daytime napping were simply to compensate nighttime sleep loss; there might be other underlying disorders that affect, for example, the wake-promoting network that leads to lengthened sleep during both daytime and nighttime.

I saw that paragraph and clearly it's intended as some sort of advertence to the correlation/causation thing, but the thing is - if they're coming out and saying that there's merely an association here, so what? No shit? That's like somebody coming out with a study that says that there's a correlation between being alive and dying - of course there is, but it isn't an interesting question nor is it an interesting scientific relationship (in my opinion at least).

I can remember taking a neuroscience unit in my first year of uni and spending a few weeks on how important sleep is for both acute cognitive function, and longer term maintenance that is needed to deal with all the metabolites and waste products that result from such an energetic organ like the brain. This was more than 5 years ago, and yet even then it had been demonstrated that if you take mice and subject them to sleep deprivation, they will develop neurodegenerative diseases at much higher rates, and much earlier, than controls. So what exactly is this study doing? Taking longitudinal data that shows a relationship between poor sleep and neurodegenerative diseases. 2015 called and it wants its conclusions back.

Basically I'd want to see an actual experimental study where they aren't asking participants qualitative questions about their sleep quality, quantity, etc, as if individuals in the early throes of Alzheimer's could even be expected to give accurate answers. I mean honestly: Imagine asking a person with dementia to rate the previous night's sleep amount and quality on a scale of 1-10. It's laughable.

Most longitudinal studies are lazy, and to me this paper is just publishing something to publish it (welcome to modern academic life) - I cannot see how this furthers our understanding of anything.

To me the study is interesting in that it found an association between the duration of daytime napping and the progression of dementia and that those two feed into each other. While it's true that there have been studies that linked poor sleep to cognitive decline, the study being discussed here, in my opinion, offers a new insight that should not be dismissed out of hand.

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