Over the last decades, technological platforms such as Facebook, Twitter or Instagram, which we know as social networks, have revolutionised the way in which many people share digital content and communicate with others. Beyond satisfying the interest in accessing information through the internet, the design of most of these platforms seeks to keep users connected for as long as possible in search of news, social approval and other behavioural design strategies. Social media use is particularly prevalent among younger generations of digital natives and, despite the benefits it can undoubtedly have, it is sometimes a cause for concern for reasons ranging from exposure to inappropriate content, reduced time available for other important matters - such as personal relationships, study, physical activity or rest - and, perhaps in some cases, the development of mental disorders such as addictions. 

The study just published in BMJ reviewed the results of 126 papers published in scientific journals that investigated the association between time spent on social networks and access to certain content and a range of adolescent health risk behaviours, such as tobacco, alcohol and other drug use, gambling, sexual risk behaviour and antisocial behaviour. 

Although many of the papers included in the review were based on cross-sectional designs or had other methodological limitations that do not provide definitive evidence of a cause-effect relationship, the results of the review show that adolescents who spend more time on social networks are more likely to use tobacco, alcohol and other drugs, more likely to engage in risky sexual behaviour and antisocial behaviour, and more likely to participate in gambling. Furthermore, the results of the review reinforce the findings of other studies that have found that exposure to content depicting the use of tobacco, e-cigarettes or alcohol is associated with an increased likelihood of using these products. 

Although further research is still needed to demonstrate the effective contribution of time spent on social networks and exposure to certain content on the development of health risk behaviours such as the use of tobacco, alcohol and other drugs (it is quite possible that an inverse relationship leads adolescents with health risk behaviours to spend more time on social networks and to search for content related to these behaviours), the results of this and other research justify the need to strengthen preventive measures that help to set limits on access to social networks in childhood and adolescence, avoid certain marketing and promotional campaigns aimed at minors and develop activities that make use of adolescents' interest in social networks to effectively disseminate preventive and health-promoting content.