There was similar experiment with teenagers and cell phones. The conclusion was cell phones were like crack at least as far as their neural pathways were concerned. The kids without the phones reported things like feeling they had lost an arm, heightened anxiety, itchy fingers, etc.
Useless unless double-blind. Kids will make shit up to prove the point that they want to prove.
Personally I find time spent away from the internet to be very pleasant; it's just a matter of engineering sufficient distractions.
Double-blind? You are taking cell phones away how are you going to make that double-blind? Or any kind of blind?
No, you can't. That's the point, we'll never really know.