There remains "little association" between technology use and mental-health problems, a study of more than 430,000 10 to 15-year-olds suggests.
The Oxford Internet Institute compared TV viewing, social-media and device use with feelings of depression, suicidal tendencies and behavioural problems.
It found a small drop in association between depression and social-media use and TV viewing, from 1991 to 2019,
There was a small rise in that between emotional issues and social-media use.
"We couldn't tell the difference between social-media impact and mental health in 2010 and 2019," study co-author Prof Andrew Przybylski. said.
"We're not saying that fewer happy people use more social media.
"We're saying that the connection is not getting stronger."
And this was a warning to regulators and lawmakers focusing on commonly held beliefs about the harmful effects of technology on young people's mental health.
Participants, in the US and UK, graded their own feelings using set questions with sliding scale responses.
And they were asked about the duration of social-media or device activity but not more specifically how they had spent that time.
The paper is published in the journal Clinical Psychological Science.
In January 2021, a study suggested heavy social-media use was linked to negative well-being and self-esteem among teenagers.
Other factors affecting young people's mental health include the coronavirus pandemic.
And the UK government has announced a £500m investment in mental-health services, with £79m earmarked for children and young people.