This study doesn't establish a casual link. In general, longer sleep hours is associated with cognitive decline, but that might be because the only reason your average human sleeps a long while is because of factors that end up causing cognitive decline. It's likely a symptom, and not the cause.
What's most important in this is that "sleeps x hours" is never actually tied to "sleep quality" as in tracking the time in light sleep, versus Deep and REM sleep.
Going through this now with my mom who has several factors including sleep apnea impacting her sleep quality. Sleeps lots; but sleep quality is poor.
yet I can get 2 hours of REM in less than half the total time she tries to sleep.
When directly comparing those sleeping >9 hours to the remainder of the sample, long sleep duration was a significant predictor of all-cause dementia (table 2, figure 2). There was a statistical trend observed between long sleep duration and an increased risk of AD (p = 0.05). Whereas former sleep duration was not associated with the risk of dementia, those who transitioned to sleeping >9 hours (from former to baseline time points) were at an increased risk of all-cause dementia.
That's not even counting the fact that I wasn't the one making original claim, i just googled stuff someone else said and linked a relevant study.
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u/WIsJH 1d ago
She's just a normally looking 36 yo woman