I am running a forum with a very young user group (primarily 9-17) and there are some users that are simply overusing my community:

Some of them are online all day, every day. While I appreciate their interest in my community and know that they found friends in there I am concerned about their real life. Staying online all day cannot be good for their real life, health and school grades.

Note that the community is located in Europe, I am not affected by COPPA and the parents do not necessarily know about their membership.

Should I do something against this or is this none of my business and their parents should keep an eye on them?