Parents can recognize that their children are overtaxed by television content through certain telltale signs.

They include nail biting, twirling the hair, shutting eyes, holding the ears, hiding behind a chair and red cheeks and ears when a child is watching television, according to Germany's association for paediatricians, based in Munich.

The organization says parents should be consistent about controlling their children's media consumption. Children under three should not watch any television at all because they cannot process visual things.

"Basically, a child should only see what they can understand and grasp," said Thomas Fendel of the association.

Television should be limited to 30 minutes a day for three to five-year-olds and to 60 minutes a day for six to nine-year-olds. The recommended maximum increases to 90 minutes for 10 to 13-year-olds and children 13 and older should be limited to two hours, the association said.

Parents can keep track of watching times by using a timer.