2/3 of Teens leave their electronics on at night. This may not seem very important but kids who use electronic close to bedtime are 200% more likely to be excessively sleepy during the day--leading to poor grades, mood swings, and anxiety.
The RULE in my house is that they need to shut their electronics (phone, Kindle, Computer, DS), whatever they are on down an hour prior to bedtime.
Goddess and Handsome go to bed at 9 which means that the electronics are off at 8. It isn't something they like but the rule is followed every school night.
Set a curfew! Tell them they can read quietly, listen to music or even watch something together as a family. Eventually they will learn this is the way it is going to be!