A review released today, which analyzed 173 strong research papers and nearly three decades of research, finds that 80 percent of studies agree that heavy media exposure increases the risk of harm to children, including obesity, smoking, sex, drug and alcohol use, attention problems and poor grades.

Some of the links are very strong. 93 percent of studies found that children with greater media exposure have sex earlier. Authors say the soundest studies are those linking media use with obesity.

The review provides overwhelming evidence of the importance of limiting children's use of media, and teaching them to critically evaluate the ever-growing volume of text, images and sounds with which they are bombarded.