Here is a great article!
http://www.ecswe.org/downloads/publications/QOC-V3/Chapter-4.pdf
You're right about the peer reviewed studies on the cocaine, but I have seen non-peer reviewedstudies where the same areas of the brain are "lit" up. Maybe it's fear mongering, but it's working on me. I'm very wary of how addictive screens are, heck I'm typing this on my iPhone and will probably scroll some social media platform after this.
I know it's just vacation, but I was just trying to find out if my kid can play in there for 3 hours or 1? I think I'll do a try and see approach. If he plays with kids and toys, I'll comfortably drop him off for long periods of time. If he's starring at a screen the whole time, probably short burst.
Any study that isn't peer reviewed is that way for a reason, it won't stand up to the peer review process. Anyone can set up the right set of conditions to "prove" anything they want, if they have the right people in their study.
Here's the thing, researchers draw a lot of correlations here, but I don't see them adequately showing causality. I honestly don't think a lot of what they are measuring is 100% due to the screen. Screens are just one symptom of a larger problem, parent's lack of engagement with their children and their unwillingness to see that they are playing with other kids regularly. No one is willing to just turn their kids out to play anymore(and rightly so), and in most households both parents work, so there isn't time to take them for supervised play. Kids are finding ways to entertain themselves, alone. They have been doing it for decades, screen are just the latest manifestation of that. Most kids used to go out and play with other kids to entertain themselves. That avenue has been cut off for most kids these days. I don't think screens would be the issue they are if this wasn't the case.
I was an only child of working parents, and when I was young we didn't live in a safe neighborhood where I could go out and play with other kids. I didn't have a screen to turn to, but I was definitely too sedentary. I didn't have the "social interaction" these studies talk about. When mom got home from work she was focused on doing what had to be done. I entertained myself, with what I had inside. There were days when I only surfaced from books to eat. Screens are just the latest manifestation of what has been going on for a long time. I know that studies show that screen time effects the brain, but have we looked at the same brain engaged in reading a book? I bet it lights up too. It's the same pleasure center.
Don't get me wrong, I do think that limiting kids screen time and controlling the content they are seeing is a good idea. The effects on sleep in particular are concerning to me and I think would bear further study. I don't think that screens are any more addictive than anything else kids have been doing for entertainment. I think that the fact that most kids have instant access to them at all times is an issue. My kid grew up with tv, ipod, ipad, and had an iphone from the time she was 10. She also danced from the time she was 3. She found her passion there and was in the studio several hours a week by the time she was 8. She is a straight A high school student handling an International Baccalaureate course load and 15 hours of dance a week. I know dozens of others just like her. I don't think screens are going to destroy our kids. I think WE have to take the time to see to it that our kids get the engagement they need, and limiting screen alone isn't going to do that.
I know a lot of this is anecdotal and not scientific evidence of anything, but I share it more to show you where my perspective is coming from.