I think there are big questions on what screen time actual is though. Isn't general computer time essentially social media? At least for most people? Most people also aren't watching documentaries on TV or doing things that exercise the brain. All admit I didn't read your sources but I'm assuming reading books isn't detrimental so it's probably not the sedentary nature of the activity (I could be completely off). I do think that since these days we use computers so much that it does warrant breaking down the activity.

Does anyone have a study that does do this comparison?