Families advised to ban screens at bedtime
The guidance has been published by four chief medical officers, including Scotland's Dr Catherine Calderwood.
It also warns parents that they should never assume a child is happy to have their photo published online.
Meanwhile the Scottish government has announced it will produce its own guidance on the healthy use of social media and screen time for young people.
It comes after links were made between the suicide of teenager Molly Russell and her exposure to harmful material on Instagram.
Her father has said he believes the Facebook-owned platform "helped kill my daughter".
England's Health Secretary, Matt Hancock, is due to meet bosses at Instagram over the handling of self-harm and suicide content.
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