It is difficult and probably impractical to have draconian limitations on screen time, and previous guidelines have been based mainly on passive viewing of TV screens, but I’ve seen enough kids showing up with back pain and with headaches due to eye strain as well as dry eyes and blurry vision from excessive use of mobile devices, not to mention difficulty with sleep onset, as well as the many adverse effects of being sedentary that it’s clear that there should be some limitations.

A Reconsideration of Children and Screen Time • 2016 Mar 21 • Perri Klass, M.D. • New York Times