Children involved in after-school activities, including sport and music lessons, are more likely to feel happier and healthier than those glued to a screen, a new study has found.

University of South Australia and the SA education department researchers found that children's wellbeing is heightened when they take part in extracurricular activities, even homework.

The study analysed data from 61,759 school students in years 4 to 9 looking at the average number of days each week children from lower socio-economic families were involved in after-school activities.

It measured those against wellbeing factors including happiness, sadness, worry, engagement, perseverance, optimism, emotion regulation, and life satisfaction.

Students who frequently played sport were 15 per cent more likely to be optimistic, 14 per cent more likely to be happy and satisfied with their life, and 10 per cent more likely to be able to regulate their emotions.

Conversely, children who played video games and used social media almost always had lower levels of wellbeing: up to nine per cent less likely to be happy, up to eight per cent to be less optimistic and 11 per cent to be more likely to give up on things.

Lead researcher Rosa Virgara said the research highlighted an acute need to encourage children to take part in activities other than screens.

"Helping children develop a good sense of personal wellbeing is paramount in today's uncertain environment," Dr Virgara said.

"This is especially important for primary school-aged children as they're learning about the challenges and risks that full-time school can present.

"But it's equally important for teenagers who are facing a range of physical, social and emotional changes."

Dr Virgara said screens were a massive distraction for children of all ages and whether children were gaming, watching TV, or on social media, there was something about all screens that was damaging to their wellbeing.

"It's interesting because you might think that it's the lack of physical movement that's causing this, yet our research shows that doing homework or reading, both sedentary activities, positively contribute to wellbeing, so it's something else," she said.

"In fact, we found that children's wellbeing was higher when they participated in extra-curricular activities even if they already reported being happy.

"What this shows is that we need to find ways to encourage children of all ages and backgrounds to get involved in activities that keep them away from TV, computers and mobile devices."

Dr Virgara conceded making the necessary changes was clearly a challenge with most children today brought up on devices.

"But if families can be more aware of the issues associated with screens, then perhaps we can find a better balance of screen time and other out-of-school activities," she said.