Children who consume as little as one caffeinated drink a week sleep less and show measurable differences in brain structure, according to a study of 9,632 children. The findings link higher soft drink intake to altered cortical development and subsequent mental health challenges.
Caffeine is woven so deeply into everyday life that it is easy to forget young people consume it regularly. Studies show that two-thirds of adolescents ingest the substance at least once a week, despite it remaining a completely unregulated psychoactive compound.
New research published in Biological Psychiatry: Cognitive Neuroscience and Neuroimaging sheds light on what happens when nine- to 11-year-olds regularly consume caffeinated beverages. Researchers from the Institute of Psychiatry, Psychology and Neuroscience at King’s College London examined data from 9,632 participants enrolled in the US Adolescent Brain Cognitive Development Study.
Cortex Surface Area and Sleep Duration in the ABCD Study
Children reported their weekly consumption of tea, coffee, and soft drinks, while parents documented average sleep durations. Researchers then used MRI scans to measure the thickness and surface area of the cortex—the folded outer layer of the brain responsible for cognitive processing, emotional regulation, attention, and decision-making.
The analysis revealed that greater caffeine intake is associated with a lower surface area across the cortex, even after adjusting for household income and parental educational attainment. This anatomical pattern appeared across 22 distinct regions spanning all four lobes of the brain. Noticeable differences in overall surface area emerged from as little as a single caffeinated drink per week.
We found that even fairly low levels of intake were linked to small differences in brain structure and later mental health, and lower sleep duration seems to be an important underlying link. Although we cannot comment on causality, our results do suggest that both caffeine intake, including from soft drinks, and sleep are worth paying attention to when we think about young people’s mental health.
Soft drinks served as the primary driver of these effects. Because those beverages also carry high sugar content and often accompany less healthy lifestyle habits or risk-taking behaviours, investigators cannot yet isolate the precise physiological role of caffeine from other dietary factors.
Six-Month and Eighteen-Month Mental Health Outcomes
Following the initial assessments, participants reported back on their mental health at six-month and 18-month intervals. Children with the highest caffeine intake experienced increased mental health difficulties six months later, specifically involving attention, mood, and behavioural problems.
The statistical pathway connecting these variables proved revealing. Children who consumed more caffeine slept less, which in turn correlated with a reduced cortical surface area. Shorter sleep and lower surface area together partially accounted for the connection between high caffeine consumption and subsequent mental health challenges at the six-month check-in. By the 18-month mark, only the direct link through overall cortical surface area remained statistically significant.
Independent experts urge some caution regarding the methodology. Derek Hill, a professor of digital health at University College London, noted that the study captured brain imaging at only a single timepoint. He also pointed out that relying on children and parents to report sleep duration and mental health can be less reliable than professional clinical assessments.
Scheduled Legislation and Regulatory Action in England
The findings emerge as the government prepares to implement a ban on selling high-caffeine energy drinks to under-16s in England. The forthcoming legislation will apply across shops, online retailers, and vending machines, targeting beverages containing more than 150mg of caffeine per litre, excluding standard tea or coffee.
This ban will reduce children’s opportunity to buy drinks that are harmful to their health and wellbeing, and demonstrates our firm commitment to creating the healthiest generation of children ever.
Public Health Minister Sharon Hodgson noted that thousands of children consume high-caffeine energy drinks daily, pointing to evidence that the beverages cause anxiety, disrupt sleep and concentration, and harm educational performance. The energy drink sales ban will come into force in April 2027.