That is according to the Royal Society for Public Health (RSPH) and the Youth Health Movement (YHM), whose survey of almost 1,500 young people aged 14 to 24 explored the positive and negative effects of social media on mental health.
Respondents were asked to score five leading social media platforms about the impact social media sites have on health and wellbeing across 14 criteria, including anxiety, loneliness, body image, self-identity and their impact on sleep.
As reported by the Guardian, Instagram was judged most negatively, having rated poorly on seven of the 14 measures, particularly with regard to impact on sleep, body image and fear of missing out.
However, the Facebook-owned app also scored well when it came to self-expression, self-identity and emotional support.
Meanwhile, YouTube was found to have the most positive impact on mental health and wellbeing after scoring well in nine of the 14 categories – and was the only one of the five judged to have an overall positive impact – but it too scored badly for its impact on sleep.
Along with Instagram, Twitter, Facebook and Snapchat were found to have a negative effect, prompting the report authors to make a series of recommendations.
These included the introduction of pop-ups on sites like Facebook to warn users about heavy usage – a measure supported by 71% of survey participants.
The Royal Society for Public Health also said social media platforms should identify users who could be suffering from mental health problems by their posts, and discreetly signpost to support.
Social media platforms should also highlight when photos of young people have been digitally manipulated, which attracted the backing of more than two-thirds (68%) of young people in the survey.
"It's interesting to see Instagram and Snapchat ranking as the worst for mental health and wellbeing – both platforms are very image-focused and it appears they may be driving feelings of inadequacy and anxiety in young people," said Shirley Cramer, Chief Executive of the RSPH.
"As the evidence grows that there may be potential harms from heavy use of social media, and as we upgrade the status of mental health within society, it is important that we have checks and balances in place to make social media less of a wild west when it comes to young people’s mental health and wellbeing."
Data sourced from Royal Society for Public Health, Guardian; additional content by WARC staff