WHO Screen Time Guidelines

World Health Organization (these are the recommendations of the American Academy of Pediatrics) 

For children younger than 18 months, both recommend avoiding screen use except for video-calls. The recommendations for the caretakers of those 18 to 24 months, wishing to allow digital media, are to choose high-quality programs, accompany them, help them understand. For children aged 2 to 5 years, the recommendation is that parents/caretakers limit screen use to 1 hour per day of high-quality programs and co-view media with them, help them understand and apply it to their personal life. For children aged 6 years and older, both authorities recommend consistently limiting the time spent using media, and on the kinds of media, making sure the media does not take the place of essential health activities like rest.

• Spend designated media-free time together, such as dinner or driving, and media-free locations at home, such as bedrooms.
• Maintain ongoing communication about digital citizenship and safety, including treating others with respect online and offline.

References

Media and Young Minds. Pediatrics. 2016;138(5):e20162591. 

doi:10.1542/peds.2016-2591