This is a weird paper. They have some good data on the prevalence of poor sleep in adolescence, and also on electronic media use. They make a plausible link between media use at bedtime and delayed sleep initiation. So far, so sound.
they then import the notion of pathological media use, which they define as use which is unregulated and affects daily activities. This is diagnosed on parent report, which seems to import all sorts of subjective judgments into this category, which not, as as I’m aware, validated.
They then draw a causal link between pathological media use and the poor sleep quality. To an extent this is sensible- using electronic media at bedtime will delay sleep, but the problem is that they don’t consider why the media use has become pathological… Is the a population of young people seeking respite from mental health or family problems, having their phones blamed for their problems, when perhaps a more understanding attitude, exploring what has gone wrong for this person and their sleep, might be more helpful.