The link between social media and low mood ran mostly through sleep, harassment and body image
A national cohort study of nearly 11,000 fourteen-year-olds
Reviewed by Sian Trombley, CCCFounder, Thrive Family Company
Moderate confidence
Source citation
Kelly Y., Zilanawala A., Booker C., Sacker A. (2018). Social Media Use and Adolescent Mental Health: Findings From the UK Millennium Cohort Study. EClinicalMedicine. https://doi.org/10.1016/j.eclinm.2018.12.005
Published 1 January 2018 · Added to Thrive 26 July 2026 · Reviewed 26 July 2026
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This study did something most headlines skip: it asked which pathways carry the risk.
Published research findings
The study
Kelly and colleagues analysed social media use and depressive symptoms in the UK Millennium Cohort Study, testing mediating pathways.
What researchers examined
Whether online harassment, poor sleep, low self-esteem and body image explained the association with depressive symptoms.
What they found
Greater social media use was associated with more depressive symptoms, especially in girls. Much of the association was accounted for by disrupted sleep, online harassment and poor body image.
Thrive editorial interpretation
What this may mean for families
The mechanisms are targetable. Sleep protection, harassment response and body-image conversations matter more than blanket bans.
What this doesn't tell us
Important limitations
Observational data at a single age, using self-reported use.
Evidence confidence describes how much weight this study's design can carry — not how strongly the finding applies to any individual child or family.
Therapist perspective — Thrive interpretation, not a finding of the study
Therapist Perspective
I treat social media as a delivery system. The thing to work on is what it delivers.
Practical family considerations
Target sleep, harassment and body image rather than the app itself.
This research summary is educational and does not replace individualized medical, psychological or therapeutic advice.
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