From the NYT article:
While most of the young people in the study got good grades, 47 percent of the heaviest media users — those who consumed at least 16 hours a day — had mostly C’s or lower, compared with 23 percent of those who typically consumed media three hours a day or less. The heaviest media users were also more likely than the lightest users to report that they were bored or sad, or that they got into trouble, did not get along well with their parents and were not happy at school.
The study could not say whether the media use causes problems, or, rather, whether troubled youths turn to heavy media use.
