Our addictive feeds of fitness models, exotic travel, and photo-perfect moments don’t often match with our comparatively humdrum and badly lit lives. The discontent caused by that disconnect is enough that a growing body of research suggests social media is contributing to mental-health problems such as anxiety, depression, sleep deprivation, and body-image issues in young people, who are the heaviest users of social media.

And Instagram, which now has 700 million users globally, appears to be the social network having the greatest negative effect, according to a new report by the UK’s Royal Society for Public Health (RSPH), an independent charity focused on health education.

The report combines previously published research on the health impacts of social media with its own UK-wide survey of nearly 1,500 people between the ages of 14-24. To discover how respondents felt different social networks—Instagram, Facebook, Snapchat, YouTube, and Twitter—affected their health, both positively and negatively, it asked them about their feelings of anxiety, connection to a community, sense of identity, sleep, body image, and more.

Only YouTube had a net-positive effect among the respondents. Every other social network came back with a net-negative effect. (In order from least negative to most, they were: Twitter, Facebook, Snapchat, and Instagram.) Respondents rated Instagram in particular as having negative effects on anxiety and body image. One of the report’s authors told CNN that girls often compare themselves to unrealistic images that have been manipulated.

The report quotes one respondent as saying, “Instagram easily makes girls and women feel as if their bodies aren’t good enough as people add filters and edit their pictures in order for them to look ‘perfect.'”

Earlier research has found that the unrealistic expectations and “fear of missing out” created across our social feeds can lower self-esteem and fuel issues such as anxiety and depression. These issues are only compounded by cyber-bullying and lack of sleep, another harmful effect linked to social media. The report cites recent research published in the Journal of Youth Studies that found one in five young people say they wake up during the night to check messages, causing them to feel exhausted during the day.

The findings weren’t all bad. Nearly 70% of respondents reported that they received emotional support on social media when times were tough, and many said their accounts offered a forum for positive self-expression. They were also able to create and maintain relationships online.

The problems centered more on forgetting that what we see isn’t always reality, and the RSPH offered some recommendations based on its findings. For one, fashion brands, celebrities, and others should consider disclosing when their photos have been manipulated. It also suggested that social networks give users a pop-up warning if they exceed a certain time spent logged on. Social platforms might even identify users with possible mental-health issues based on their usage and send a discreet message on where to get help.

Not least of all, the report said more research is needed into social media’s health effects. Social’s spread among younger generations is only growing. It’s too big a force not to consider the health consequences seriously.