While an 18 year old is not as mature as we are, when you start talking about computer restrictions I think it's very important to realize that we're actually t

While an 18 year old is not as mature as we are, when you start talking about computer restrictions I think it's very important to realize that we're actually talking about an 18-year-old adult. Let the guy does what he wants, this is absurd! (fwiw I spent about that much time on the computer at that age and I turned out fine) EDIT: OP is sparse on details, if this is a "won't get a job, makes mommy pay for everything" situation then that does warrant some form of action, but then the computer is not the cause of the issue - someone who refused to get a job and spent 9 hours a day reading economy text books would still be a problem. There might be social anxiety or depression or some such at play - talk to the guy, be gentle, be supportive, seek professional help if it's really a serious problem. If the guy is in school you really just don't have a basis to hassle him about what he does in his free time. "My house, my rules" is the creed of authoritarianism parents, trying to dictate the life of an 18 year old will only foster resentment.