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Across hundreds of studies, researchers have asked whether the rapid spread of smartphones coincides with – or causes – rising anxiety, depression and self-harm in young people. The short answer is: there is some evidence of harm, but on average the effects are small, highly variable, and we still lack high-quality causal data.
What the strongest reviews say
• An international panel that reviewed 226 studies concluded that “associations are generally small and heterogeneous; the overall quality of evidence is low to very low” and that causal claims “cannot yet be made with confidence.” [1]
• A 2023 narrative review in the Journal of Child Psychology and Psychiatry also found “little consistent evidence that screen use is intrinsically harmful,” although some sub-groups appear vulnerable and certain kinds of use (e.g., late-night doom-scrolling) look riskier than others [4].
Size of the associations
• In a U.S. population survey of 40,000 youth, adolescents who used screens ≥7 h/day scored 0.4–0.7 SD lower on well-being than those who used screens <1 h/day, but screen time explained only 1–2 % of the total variance in well-being [2].
• Three time-use-diary datasets from the U.K., U.S. and Ireland showed that digital‐technology use accounted for at most 0.4 % of the variation in well-being – a statistical effect comparable to the one produced by regularly eating potatoes or wearing glasses [3].
Directions of causality
• Cross-lagged panel studies generally find bidirectional links: adolescents with poorer mental health later spend slightly more time online, and very heavy users show slightly poorer mental health later on; effect sizes in both directions are small [4][6].
• Experimental data are sparse. Short-term trials that restrict social-media use often find modest mood or sleep benefits, but samples are small and follow-ups brief [7]. Definitive causal evidence therefore remains elusive.
Who seems most at risk?
• Girls, younger adolescents (11-13 yrs), teens who already struggle offline, and those exposed to online harassment or social comparison show stronger negative links [1][4][6].
• Night-time phone use and passive or appearance-focused scrolling predict worse outcomes than active, socially supportive use [4].
Possible mechanisms (still under study)
• Sleep displacement and circadian disruption
• Social comparison and body-image pressure
• Cyber-victimisation and hate content
• Displacement of physical activity or face-to-face interaction
Putting the pieces together
• Smartphones are not toxic for every teenager, nor are they benign for all. The average correlation with mental-health indicators is negative but very small.
• Particular patterns of use, contexts and vulnerable individuals can experience meaningful harms, while many teens derive social connection, information and entertainment benefits.
• Because current evidence is largely correlational, stronger longitudinal and experimental work – with finer-grained measures of content, context and individual difference – is needed before firm causal claims, let alone sweeping policy prescriptions, can be justified [7].
Practical implications while the science catches up
• Prioritise sleep: keep phones out of bedrooms after lights-out.
• Focus on “how” and “why,” not just “how much”: encourage active, purposeful online engagement and discourage passive scrolling.
• Watch for warning signs in vulnerable youth (e.g., cyber-bullying, appearance anxiety) and intervene early.
• Partner with platforms for safer design and better data access so that researchers can answer the causal question more definitively.
In sum, smartphones can harm adolescent mental health, but for most teens the impact is small and contingent. Targeted, evidence-based guidance is more appropriate than blanket fear or complacency.
Sources
[1] A Consensus Statement on Potential Negative Impacts of Smartphone and Social Media Use on Adolescent Mental Health – concludes that links are small, heterogeneous and not yet demonstrably causal. https://osf.io/preprints/psyarxiv/b94dy
[2] Twenge & Campbell (2018) “Associations Between Screen Time and Lower Psychological Well-Being…” – finds heavier screen use linked to lower well-being; effect sizes explain 1–2 % of variance. https://www.sciencedirect.com/science/article/pii/S2211335518301827
[3] Orben & Przybylski (2019) “Screens, Teens, and Psychological Well-Being…” – very large diary studies; associations <0.5 %. https://journals.sagepub.com/doi/10.1177/0956797619830329
[4] Odgers & Robb (2023) “Adolescent Mental Health in the Digital Age…” – review stresses small average effects, importance of content and context. https://pmc.ncbi.nlm.nih.gov/articles/PMC8221420/
[5] Tsakiris (2024) “Behind the Scenes of the Consensus Statement…” – describes methodological disagreements and why panel settled on cautious wording. https://www.centerconflictcooperation-newsletter.com/p/behind-the-scenes-of-the-consensus
[6] Chatterjee (2023) NPR “The truth about teens, social media and the mental-health crisis” – journalists interview experts; emphasises bidirectional, nuanced evidence. https://www.npr.org/sections/health-shots/2023/04/25/1171773181/social-media-teens-mental-health
[7] Abbott (2025) Nature “Are screens harming teens? What scientists can do to find answers” – argues that better designs and platform data are needed to reach causal conclusions. https://www.nature.com/articles/d41586-025-00991-7
[8] Haidt (2024) “The Anxious Generation in the Classroom” (Aporia Magazine) – presents a strongly negative view, attributing recent spikes in anxiety and depression mainly to smartphones; illustrates the breadth of opinion in the debate. https://www.aporiamagazine.com/p/the-anxious-generation-in-the-classroom