The US has the most sleep-deprived pupils in the world, and the late-night glow of smartphones and laptops is probably contributing to a lack of slumber. A study out of Boston College finds that US students are sleep-deprived at a rate almost 30% higher than the international average, with 73% of 9- to 10-year-olds and 80% of 13- to 14-year-olds not getting enough snores. And those students who did get enough rest sat through classes that were dumbed-down to accommodate their sleepy peers.
"I think we underestimate the impact of sleep," one researcher tells the BBC, noting children who get more sleep perform better in math, science, and reading. "It's the same link for children who are lacking basic nutrition." Experts say the light from smartphone and laptop screens at night—close to the eyes—is posing a barrier to the onset of sleep, which may account for more technologically advanced countries faring worse in the study. (Read more students stories.)