I feel like sleep quality and phone addiction are very different, even if somewhat connected.
I would agree, though, that improving sleep quality would definitely improve cognitive function.
But removing phones would only help if it’s degrading sleep. If phone addiction has no impact on sleep (e.g. the parents still enforce regular bedtimes), then I would not expect that much, if any, cognitive improvement. Not quickly, anyway.
Either way, these two need to be studied independently to know for sure.
I agree that this study didn't separate the two very well, but it's a difficult task to be fair.
They found that the kids' bed times were far earlier without phones, but was that a short term effect? Was it an effect of being observed and measured? If the parents valued their kids' sleep, why was the average bed time of 12 year old kids after 11pm pre-ban? You could blame that lack of sleep on phones if it made you feel better I suppose, but it's clearly not the whole story.
I would agree, though, that improving sleep quality would definitely improve cognitive function.
But removing phones would only help if it’s degrading sleep. If phone addiction has no impact on sleep (e.g. the parents still enforce regular bedtimes), then I would not expect that much, if any, cognitive improvement. Not quickly, anyway.
Either way, these two need to be studied independently to know for sure.