Very frequent use of social media may compromise teen girls’ mental health by increasing exposure to cyberbullying and reducing sleep and physical exercise, according to a new study.

In a report published by British medical journal The Lancet, researchers concluded that regular use of social networks such as Facebook and Instagram may disrupt sleep and exercise as well as increase the risk of online bullying.

“Our results suggest that social media itself doesn’t cause harm, but that frequent use may disrupt activities that have a positive impact on mental health such as sleeping and exercising, while increasing exposure of young people to harmful content, particularly the negative experience of cyber-bullying,” according to Professor Russell Viner from University College London’s Great Ormond Street Institute of Child Health, who led the research.

The report authors tracked almost 10,000 adolescents, aged 13-16, over three years in England between 2013 and 2015.

Each year the youngsters reported the frequency with which they accessed or checked social media.

As well as questions about their social media habits, the teens were asked about their experiences of cyberbullying, sleep and physical activity.

In both sexes very frequent social media use, defined in the study as using social networks, instant messaging or photo-sharing services three or more times daily, was associated with greater psychological distress, but less so in boys.

“The clear sex differences we discovered could simply be attributed to girls accessing social media more frequently than boys, or to the fact that girls had higher levels of anxiety to begin with,” co-author Dasha Nicholls from Imperial College London said.

“Cyberbullying may be more prevalent among girls, or it may be more closely associated with stress in girls than in boys.

“However, as other reports have also found clear sex differences, the results of our study make it all the more important to undertake further detailed studies of the mechanisms of social media effects by gender.”

Half of all mental illnesses start by the age of 14, making adolescence a crucial period for promoting mental health, the report authors said.

But there is some evidence that social media use can positively influence health, for example by reducing social isolation.

“Social media use among youngsters need not be as negative as often assumed,” Ann DeSmet from Ghent University, Belgium, added.

“If the displacement of healthy lifestyles and cyberbullying can be attenuated, the positive effects of social media use, such as encouraging social interactions, can be more endorsed.

“This paper demonstrates sleep, cyberbullying and physical activity may be important lifestyles to target in protecting and improving youth mental health.”

For the study, scientists analysed data from three sets of interviews with teenagers from nearly 1,000 schools across England.

The survey did not capture how much time the teenagers spent using social media.

In the second year of the study, participants completed the General Health Questionnaire, for which a high score indicates psychological distress.

In the final year, participants were surveyed about three aspects of their personal wellbeing - life satisfaction, happiness and anxiety, using standard questions supplied by the U.K’s Office for National Statistics.

When the authors found any significant associations between the teenagers’ social media use and psychological distress or wellbeing, they assessed the degree to which this could be attributed to cyberbullying, sleep and physical activity.

In 2013, of 13,000 children interviewed, 43 per cent of boys and just over half of girls used social media multiple times a day. By 2014, this had increased to 51 per cent and 68 per cent respectively.

In 2015, 69 per cent of boys and 75 per cent of girls used social media multiple times a day.

The study was conducted by researchers from UCL Great Ormond Street Institute of Child Health and Imperial College School of Medicine in London, England.