While previous research has suggested that students attending afternoon classes often perform better academically due to alignment with their biological clocks, a new study shows this advantage does not extend to children with attention deficit hyperactivity disorder (ADHD) or related symptoms. For these students, changing school shifts—morning to afternoon or vice versa—does not significantly improve academic outcomes.
The study analyzed 2,240 Brazilian students aged six to 14, assessing reading and writing skills, school setbacks such as suspensions or grade repetition, and ADHD symptoms. Data were examined over three years, both in aggregate and through subgroup analyses.
“The results indicate that shifting school schedules shouldn’t be considered an effective intervention for treating ADHD,” said Maurício Scopel Hoffmann, head of the Department of Neuropsychiatry at the Federal University of Santa Maria and researcher at the Institute of Developmental Psychiatry for Children and Adolescents. “For children with attention deficits, studying in the morning or afternoon does not significantly change academic performance, as the underlying difficulties persist.”
The study found that while afternoon classes benefit students with few or no ADHD symptoms, students with ADHD show no measurable improvement regardless of shift. Morning classes lowered performance for students without ADHD but did not worsen outcomes for those with significant attention challenges.
Published in European Child & Adolescent Psychiatry, the research is part of the Brazilian High Risk Cohort Study (BHRCS), an epidemiological study supported by the São Paulo Research Foundation (FAPESP) that has tracked over 2,500 students aged six to 24 at risk for mental disorders in Porto Alegre and São Paulo.
According to Brazil’s Ministry of Health, roughly 7.6% of Brazilian children have neurodevelopmental disorders, including symptoms of inattention, hyperactivity, and impulsivity. Children with ADHD often learn more slowly, affecting reading, writing, and math skills.
Hoffmann emphasized that non-pharmacological strategies can help these students succeed academically. “Untreated children with ADHD can accumulate lifelong challenges. They are more prone to injuries, slower learning, grade repetition, and social difficulties. School struggles can snowball into anxiety and depression in adulthood,” he explained.
“Our initial hypothesis was that school shift might influence the relationship between ADHD and performance. However, our results indicate a ‘ceiling effect’—studying in the afternoon offers no measurable benefit for students with ADHD. They face difficulties regardless of class timing, so changing shifts should not be considered a strategy to overcome the disorder’s effects,” Hoffmann added.
