I feel like this is a oddly biased study, as there are two major influencing factors that would have changed Sophie's behaviour.

1. The limits, creating a hard limit, obviously screen time is going to reduce, you can also make my battery a 10th of the size and achieve the same result, it doesn't mean I'm better off or happier.

2. The surveillance. The writer, as a complete stranger to the teenager (for the most part) tracking her daily usage AND commenting on it whilst sharing it with her mother, is enough to change her behaviour dramatically.

I'd like to see how well self imposed limits work, and if there's any beneficial change people notice.