Sugar rush or sugar crash? Experimental evidence on the impact of sugary drinks in the classroom

Sugary drinks in schools have been demonized for their potential long-term contribution to rising obesity rates. Surprisingly, there is only little evidence on the immediate effects of sugary drinks in schools. This paper provides experimental evidence on the in-class effects of sugary drinks on behavior and student achievement. We randomly assigned 462 preschool children to receive sugary drinks or artificially sweetened drinks and collected data before and after consumption. Our findings suggest that the consumption of one sugary drink induces an initial “relaxing” effect for boys, before making them more restless. Girls' behavior is not significantly affected. We find a negative effect on student achievement for boys and a positive effect for girls. We show the robustness of the results across two field experiments.