A new study suggests that the more teenagers watch television, the more likely they are to develop depression   as young adults.But the extent to how much TV may be to blame is a question that the study leaves unanswered. The researchers used a national long-term survey of adolescent health to look into the relationship between media use and depression.They based their findings on more than 4,000 adolescents who were not depressed when the survey began in 1995. As part of the survey, the young people were asked how many hours of television or videos they watched daily.They were also asked how often they played computer games and listened to the radio. Media use totaled an average of 5 and one half hours a day.More than 2 hours of that was spent watching TV. 7 years later, in 2002, more than 7 percent of the young people had signs of depression.The average age at that time was 21. Brian Primack at the University of Pittsburgh medical school was the lead author of the new study.He says every extra hour of television meant an 8 percent increase in the chances of developing signs of depression. The researchers say they did not find any such relationship with the use of other media such as movies, video games or radio.But the study did find that young men were more likely than young women to develop depression given the same amount of media use. Doctor Primack says the study did not explore why watching TV causes depression.But one possibility, he says, is that it may take time away from activities that could help prevent depression, like sports and socializing. It might also affect sleep, he says, and that could have an influence. The study was just published in the Archives of General Psychiatry. In December, the journal Social Indicators Research published a study of activities that help lead to happy lives.Sociologists from the University of Maryland found that people who describe themselves as happy spend less time watching television than unhappy people.The study found that happy people are more likely to be socially active, to read, attend community services and to vote. The study done by the sociologists from the University of Maryland was mainly meant to   _  .
tell the difference between happy and unhappy people prove the relationship between TV and depression stress the importance of being socially active provide a happy recipe   for all people