In a study of over 2,300 junior high school students in Barcelona, Castellis-Cuixart et al found that most ate their meals alone during the week, and that 40% watched TV during breakfast, 39% watched during lunch, and 59% watched during dinner.
Salmon et al implemented a 9 month intervention to reduce television viewing among 164 ten year old Australian children. Follow-up surveys found that putting limits in place and encouraging children to turn the television off when their specific program ends helped decrease the amount of television they watched everyday by up to 30 minutes. They determined that social and family factors are important considerations when developing television interventions.
In a study of over 9,000 junior high school students in Japan, Alexandru et al found that teens who watched a lot of TV or played more video games took longer to fall asleep than teens who watched and played less. You can see other studies on media and sleep in the CMCH Database of Research.