India, Oct. 5 -- Children and young adults who use phones, social media and games compulsively are about twice as likely to be depressed or anxious, to harm themselves, to sleep badly and to feel lonely. That is the finding of the largest review of the evidence to date, which covers more than 9 million people under 25.

The analysis, published Monday in eClinicalMedicine, a Lancet journal, pools 121 earlier reviews. It anchors a three-paper series in The Lancet by 13 public health researchers. They concede the data can't prove that screens cause the harm but argue the pattern is consistent enough, and the exposure common enough, for governments to act without waiting for proof.

"Governments have let technology companies write their own r...