One of the main concerns of parents is their children’s ‘screen time’. There are numerous studies outlining the adverse effects of excessive screen time on children. Dimitri Christakis, a pediatrician and an expert in child development, provides guidance for parents for children’s screen time.
Christakis advises parents to use slow-paced apps and to restrict screen time to 30 minutes a day for children. He notes that pacing is particularly important for brain development and that apps with frenetic graphics and frequent shifts in scenes are harmful for children. He notes that parents should be mindful of being good role models for children and to not excessively use phones and other screens in front of the children, who easily mimic their parents behaviours.  He asserts that when screen time replaces conversation during family time, there is a negative affect on the children’s cognitive, social, and emotional development, which may be irreversible.
http://www.vogue.com/13364743/screen-time-rules-for-kids/