Writing in the Archives Of Disease In Childhood, Dr Sigman said such extensive use of televisions and tablets could also lead to attention problems and other psychological difficulties.
The amount of time spent in front of a screen could also adversely affect children's social relationships.
He said many parents use the devices as "electronic babysitters" as a means to occupy their children.
"Screen time appears to have created the three-parent family," he added.
More top news
Dominic Chappell, the man who bought BHS for £1 from Sir Philip Green, is to be prosecuted by The Pensions Regulator.
The 5,000 ecstasy pills had an estimated street value of £36,000.
Police say it is "too early" to know if the body is that of journalist Kim Wall, who is believed to have died on board an amateur submarine.