Researchers at the Norwegian University of Science and Technology (NTNU) and NTNU Social Research followed hundreds of children over four years to see if they could find a link between physical activity and depression.
Almost 800 children were examined when they were six years-old and conducted follow-up examinations with about 700 of them when they were eight and 10 years-old.
Physical activity was measured with accelerometers (a kind of advanced pedometer) and parents were interviewed about their children's mental health.
Physically active six- and eight-year-olds showed fewer symptoms of depression when they were examined two years later.
The message to parents is that limiting children's TV or iPad screen time is not enough; you need to facilitate physical activity. Try going for regular bike rides or playing outside with your kids.