Toddlers who watch too much television are more likely to suffer later behavioural problems - but the damage can be reversed, say researchers.
The Johns Hopkins University experts found that under-fives who watched over two hours a day increased their risk.
However, young children who watched too much, but cut back by five years old, removed the risk, the study in the journal Pediatrics suggested.
A UK expert said the level of damage could depend on the individual child. There is fierce debate over the effect of exposure to television on young children, with increasing evidence to suggest that watching substantial amounts can affect behaviour.
In the US, the American Academy of Pediatrics recommends that children under two years old watch no television, with older children restricted to no more than two hours a day.
The study, from the Johns Hopkins Bloomberg School of Public Health, analysed data for 2,700 children, asking their parents about viewing habits and behaviour at two and five years old.
Source - BBC