Social media can make children more likely to have eating disorders or try drugs because it makes them more impulsive, a new study suggests.

Too much social media - which includes Facebook, Twitter, WhatsApp, YouTube, Instagram and SnapChat - makes them more impulsive, often leading to bad decisions that will affect them for the rest of their lives, warn scientists.

Children spending a significant amount of time looking at screens, and not getting enough sleep, are most vulnerable, the study found.

Lead author Dr Michelle Guerrero, a paediatrican at the University of Ottawa, said: "Impulsive behaviour is associated with numerous mental health and addiction problems, including eating disorders, behavioural addictions and substance abuse."

Her team analysed more than 4,500 eight to 11 year olds. Those who used smartphones more than two hours a day and slept less than nine hours a night were more impulsive.

The results were based on the participants' self reported scores on eight traits such as perserverance, seeking out thrills, setting goals, being sensitive and acting rashly.