At What Age Should Children Get Smartphones? — Reading the Twenge/Haidt Debate to Design Your Own Approach

Audience
Parents of children in early-to-middle primary school; parents currently deciding whether to provide a device, or already feeling uncertain about one already given
Target length
~1,600 words
Status
Draft v1 (translated from Japanese v1)
Original
../149_screen_time_age_design.md

Lead

"At what age is it okay to give a child a smartphone?" As of 2025, science has not produced a definitive answer to that question.

Researchers are still in active dispute. On one side is the claim that screen time has serious negative effects on adolescent mental health; on the other, that the effect sizes are statistically small and causal relationships have not been established. National policies span a wide range — Australia's law banning social media for under-16s, the EU's Digital Services Act, the UK's Online Safety Act — but the interpretations of the underlying evidence that inform those regulations differ substantially.

This article is about reading that debate in a way that is useful to a family making a decision. The goal is not to wait for science to settle the question but to understand the current state of the evidence — its quality and its limits — well enough to build a household approach on it.