Castelo · PNAS nexus 2025 · randomized controlled trial · n=?

Blocking mobile internet on smartphones improves sustained attention, mental health, and subjective well-being.

Cited 34 times in the scientific literature.

Level 2 - randomized trial

Individual randomized controlled trial

PubMed 39967678 · doi:10.1093/pnasnexus/pgaf017 · record verified 2026-08-31

What was done

Researchers conducted a month-long randomized controlled trial to assess the causal impact of continuous smartphone internet access. Using a dedicated mobile application, mobile internet was blocked on participants' smartphones for 2 weeks with objective compliance tracking, while retaining cellular calls, SMS, and non-mobile internet access (e.g., desktop computers). Outcomes included objectively measured sustained attention, mental health, and subjective well-being, along with mediation analyses of time use.

What was found

The intervention improved mental health, subjective well-being, and objectively measured sustained attention, with 91% of participants improving on at least one outcome. Mediation analyses showed the benefits were partially explained by increased time spent socializing in person, exercising, and being in nature. Numerical values for baseline scores, effect sizes, and confidence intervals were not reported in the abstract.

Why it matters

This study provides experimental, causal evidence that the ubiquitous availability of mobile internet—rather than phone connectivity itself—adversely affects attention, well-being, and daily time use.

Limits

The abstract does not provide the sample size, demographic characteristics, recruitment setting, or attrition rates. Participant blinding was not possible given the nature of the intervention, and long-term durability of the improvements after the restriction ended was not reported.

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