Here's my anecdote. My parents tried to limit video games (but not tv, they weren't very rational) to some amount of hours a day. Only result was that I hated it, it made me resent them at the time, and I'd do what I could to get around it. I don't think I'm an iota better off for it. They'd try to pull the same nonsense with the computer too which ended up being what got me a successful career. It was detrimental if anything and made me not respect them because I could tell all along it was unsubstantiated BS that somehow video games and computers were "bad" for you. I highly recommend just letting them sort out what they want to do with their time. A restriction of a half hour before bed maybe, to not disrupt sleep, fine, but what does the morning have to do with anything?