limits on screen time?

The dilemma of the day is computer/game/screen time and how much we will control that. The first question would be whether it is bad for the teenagers to have control of how much time they spend on the computer. The second question is whether it is bad for the family to not have limits on computer/game/screen time. The third question is whether it is bad for my mental health to have the sounds of TV and games going a lot of the time that the teenagers are home.

With foods and health issues it is easier to set limits. It is harder with entertainment. Research seems to show that for young children less screen time is best. I don't know of any similar research with teens, other than that active recreation helps maintain a healthy body. If the teens are physically active, do I need to limit their screen time?

Issues:

• How much helping around the house do they need to do to make life workable for the whole family?
• If I would limit screen time would that make it more likely for them to play music or read or draw or write or talk to me? Is it important to do that? Is it imperative?
• If I set a limit, what is reasonable? Is there a way to set a limit that isn't arbitrary?
  
• How do I get away from watching the clock and nagging when the time is up? Is there a way to limit without my having to also be the enforcer?

Anyway, my time is now up so I'll ponder this more some other time.