According to the American Academy of Pediatrics all media, both foreground and background, have no known positive effects for children younger than 2 years. All the effects are potentially negative, so the academy advices you should not put your toddler in front of TV, especially to watch shows that are created just for them. Incremental exposure to television delayed development remarkably and these effects don’t disappear even at age 7 when it was expected to disappear at age 5.
Again the age at which children begin watching TV and the number of hours spent viewing screens per day has been increasingly linked to negative medical consequences and psychological changes. Anti-social behaviors are also linked to much time spent watching TV from 29 months upwards and increased viewing of screens in later years. It appears that there is a ‘dose-response relationship’ linking more hours to a greater likelihood of the child experiencing negative effects often in later years.
Every additional hour of exposure to TV on a daily basis among toddlers corresponds to a higher body mass index, higher consumption of junk food, a more sedentary lifestyle, increased victimization by classmates, future decrease in classroom engagement and success at math, according to the American medical Association journal.
Time one spends viewing screens also has medical effects on the viewer. The effects include reduced sleeping ability or sleep disturbances. The sleep-promoting hormone, Melatonin, produced in the brain is affected by media also. Researchers reported recently that depriving the average child aged 6-12 of their video games, computers and TV sets resulted in a 30% increase in the production of melatonin.