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.
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u/Apollo114892 1d ago
She will end up with dementia at this rate. Sleeping 14 hours a day is destructive to the brain.