From the NY Times http://www.nytimes.com/2010/01.....wired.html
The average young American ages 8-18 now spends practically every waking minute — except for the time in school — using a smart phone, computer, television or other electronic device, according to a new study from the Kaiser Family Foundation. The 85-page study, which includes a national sample of 2,000 young people, can be downloaded from http://www.kff.org/entmedia/upload/8010.pdf
The content is pretty interesting. There's a tremendous jump in media use that occurs when young people hit the 11- to 14-year-old age group. The amount of physical activity for all the respondents is less than 2 hours a day.