The happiness levels of nearly 10,000 girls and boys were tracked between the ages of 10 and 15. Girls who spent more than an hour a day on social media from the age of 10 were more likely to suffer problems.
What is 'bait out'?
"Bait out" pages are online groups or pages that invite users to share nude images, videos or sexual gossip about others, according to Childnet .
Users are often only allowed access to the group or page once they have shared such content.
While Facebook desperately tightens controls over how third parties access its users' data - trying to mend its damaged reputation - attention is focusing on the wider issue of data harvesting and the threat it poses to our personal privacy.
Data harvesting is a multibillion dollar industry and the sobering truth is that you many never know just how much data companies hold about you, or how to delete it.
A stalker who uploaded sexual images of a mum to social media and adult porn websites as he waged a shocking campaign of harassment has been jailed for 54 months.
It's a sensational story containing allegations of sleaze, psychological manipulation and data misuse that has provoked an internationally furious response.
Tech giant Facebook and data analytics firm Cambridge Analytica are at the centre of a dispute over the harvesting and use of personal data - and whether it was used to influence the outcome of the US 2016 presidential election or the UK Brexit referendum.
Both firms deny any wrongdoing.
Schools should play a bigger role in preparing children for social media's emotional demands as they move from primary to secondary school, England's children's commissioner says.