I have a research study for you to conduct about your teen's hours spent in their bedroom. For the next two days just strictly observe bedroom time. This includes after school time, after dinner and before bedtime. Now compare that to time spent in common rooms. If you still remember fractions, make it into a fraction:
time spent in room
time spent in family spaces
I bring this up because of a recent article in the New York Times. See link below. It seems the amount of time, girls especially spend in their room is proportional to the amount of anxiety they are experiencing. If only they were spending all this time doing their homework, but most likely they are obsessively on their phones, checking for likes, and reposts, and looking through a metaphorical magnifying glass at their selfies, their friends selfies, selfies that are friends of friends of friends....and judging how they measure up. Who's thinner, who's prettier, who has more friends, more likes, more reposts, and how do I measure up??? This does cause great stress and anxiety. And though girls may subject themselves to this kind of scrutiny more, boys can be just as bad. This is not emotionally healthy. It can be destructive to self-esteem, self concept, and the work of developing the all important task of identity. Read this article for great tips on how to counter this.