The report from the Kaiser Family Foundation goes on to discuss other issues related to the media and sleep:

“Sleep problems in middle childhood tend to be persistent. This fact raises the question as to what, if any, are the long-term effects of media use on children’s sleep. It may be, for example, that there is a critical window early on in which good sleep habits are established.

One prominent sleep researcher has argued that sleep problems in early childhood may have adverse developmental impacts that are not fully observable until years later. This researcher speculates that early sleep deprivation in children is part of the cause of Attention-Deficit Hyperactivity Disorder (ADHD).