Too much technology can prevent your tween from interacting with people in real life. It can also interfere with sleep and physical activity. Consider these suggestions for keeping their tech time in balance:
Make a ratio rule. For example, you could say, for every half hour your child spends using technology they should spend a half hour or more doing something else, preferably something involving physical activity.
Create digital-free zones. You might say, no cell phones or tablets at the dinner table or in restaurants.
Insist that devices go off at bedtime. Children could stay up for hours playing games or watching videos. They can also be awakened by texts or sleep lightly in anticipation of them. Also, try setting up a family charging station where everyone must leave their devices at a certain time in the evenings.