Why no study here settles the app-lock question
The question asks for a specific comparison: a timed app lock versus a broader cutback on phone use, in a specific group, adolescents with attention deficits. The studies available do not run that comparison. One examines how social media use, sleep quality, and school engagement relate to one another in adolescents, with attention-deficit hyperactivity disorder symptoms mentioned as part of the picture, but it says nothing about locking apps before bed or about reducing phone use generally [1]. The other is a narrative review of problematic smartphone use and academic performance, and it likewise does not evaluate either intervention [2].
That gap matters because the two approaches are not interchangeable. A 30-minute app lock targets a narrow window and a narrow set of apps, while general smartphone reduction changes total use across the day. Without a study that sets these side by side in the same group of adolescents, any claim that one works better than the other would be guesswork rather than evidence.
The indirect case for intervening at all
The reason the question is worth asking is that phone use and sleep appear connected in adolescents. The social media study treats sleep quality as a link in the chain between social media use and school engagement, and its abstract notes that time meant for sleep routines can be pushed later, disrupting rest [1]. In plain terms, the concern is that time on a phone displaces or delays the wind-down that sleep depends on.
The review of problematic smartphone use adds a second angle: it describes cognitive pathways that include attention deficits alongside sleep-related mechanisms, and it notes the role of ADHD symptoms [2]. This is a description of possible routes, not a demonstration that either bedtime app locks or general reduction fixes the problem. The review also mentions usage-reduction ideas such as blocking during study periods, which shows that blocking is discussed in the literature, but it does not report testing a bedtime lock [2].
Why attention deficits make the answer harder, not easier
Both studies flag ADHD symptoms, but neither isolates adolescents with attention deficits as a group receiving a bedtime intervention [1][2]. That distinction matters for the reader's question. A pattern found across a general adolescent sample may not carry over cleanly to teens whose attention difficulties could change how they use a phone at night or how they respond to a hard stop on apps.
The review's framing is useful here: it places attention deficits among the cognitive pathways connected to problematic smartphone use rather than treating attention as a separate issue [2]. That suggests attention and phone habits may be intertwined, but it does not tell us whether a timed lock would help this group more or less than a general reduction. The honest reading is that the mechanism is plausible and the specific comparison is untested in these sources.
What you can reasonably conclude, and what to watch for
Taken together, the studies support a cautious, indirect conclusion: sleep quality is plausibly part of how adolescent phone use affects daily functioning, including school engagement, and attention-related difficulties appear in that picture [1][2]. They do not show that a 30-minute app lock outperforms general smartphone reduction, and they do not show the reverse. Anyone presenting a firm winner is going beyond what these studies establish.
If you are weighing the two approaches, the useful next step is to look for research that directly compares them in adolescents with attention deficits, measuring sleep quality before and after each strategy. Until such a comparison exists, the choice rests on practical fit rather than on evidence of superiority, and the current studies are best read as background on why nighttime phone use and sleep are linked at all [1][2].
Sources used in this answer
Attention and sleep quality as mediators in the link between adolescents' social media use and school engagement.
Examines social media use, sleep quality, and school engagement in adolescents with reference to ADHD symptoms, but does not test bedtime app locking or general smartphone reduction.
Problematic Smartphone Use and Academic Performance in Children and Adolescents: A Narrative Review
Reviews links between problematic smartphone use and academic performance, describing attention-deficit and sleep-related pathways and mentioning usage-reduction ideas such as blocking, without evaluating bedtime app locks or general reduction.