The American Journal of Play has a collection of essays on free-play and the impact that play has on children. The experts warn that not allowing children time to participate in unstructured play is causing them harm. They say that helicopter parenting may be undermining the health and well-being of children because it robs children of the chance to play uninterrupted.
More here. To read an interview with two of the authors click here. To read the article on 'the Decline of Play and the Rise of Psychopathology in Children and Adolescents' featured in the journal click here