We told you Monday of research that found kids are well-versed in the use of mobile devices by the age of four, spending an average 22 minutes a day on them. Today, there’s a study from non-profit group Common Sense Media telling us teenagers are glued to their electronic devices and other media for as many as nine hours a day – more time than they spend sleeping, and more time than they spend with their parents and teachers. That nine hours does not include time spent using media at school or for their homework. When it comes to consuming media on screens, including laptops. smartphones and tablets, the report found teens, on average, spend more than six and a half hours on screens and tweens more than four and a half hours.