The University of South Australia study, in conjunction with the Murdoch Children's Research Institute and the National Heart Foundation, looked at what the optimal balance of physical activity, sleep and sedentary time was for kids across a 24 hour period.
Researchers looked at the overall health of 1,179 kids aged between 11-12 years, assessing their body mass index (BMI), body fat and waist girth and self-reported responses about their mental wellbeing.
While they found exercise had a bigger and faster impact on health, it was also found the same reduction (7.4 per cent) in their BMI could be achieved by sleeping an extra 52 minutes.
The same result was also achieved by adding 17 extra minutes of moderate to vigorous exercise or by cutting their sedentary time by 56 minutes.
Kids who had an additional 35 minutes exercise, or 68 minutes sleep or reduced their sedentary times by 54 minutes also saw a 'significant' improvement in their mental health.
Lead researcher Dr Dot Dumuid said the findings were an important tool for families looking for simple ways to optimise their child's health, by showing which activities provided the greatest 'bang for your buck'.
"There are many competing time demands in modern families – whether it's after school soccer, music lessons, or simply walking the family dog, finding the time to fit everything into a single day, can be a challenge," she said.
"International guidelines suggest that children need nine-11 hours' sleep, 60 minutes of physical exercise, and no more than two hours of recreational screen time per day, yet only seven percent of children are regularly meeting these goals."
Dr Dumuid added that families with little down time could look to small increases in exercise as a way to boost health, or increasing their sleep time - by moving bedtime forward. Saying the flexibility of moving between these was what made the findings so important.
"Exploring trade-offs between children's activities is a promising way for families to make healthy choices that suit their regular family schedule," Dr Dumuid added.