Spending an hour or more in front of digital devices each day has a more limited effect on 2-year-olds' growth and development than previously believed, a recent study by Japanese researchers has shown, providing fresh insight into the possible risks of the use of digital devices on toddlers.

The study also found that the negative effects of a day's screen time on young children can be reduced by letting them play outside for more than 30 minutes, according to researchers from Osaka University and the Hamamatsu University School of Medicine.

The findings came amid persisting concerns over the adverse effects of smartphone use by children, with the World Health Organization recommending in its guidelines that 2-year-olds should not be exposed to sedentary screen time — which is defined as activities such as watching TV and playing computer games — for over one hour a day.