Too many kids are returning to the playing field too soon after a concussion. How many? According to an alarming new study, from 2005 to 2008, 41% of concussed athletes in 100 high schools across the U.S. returned to play too soon, under guidelines set out by the American Academy of Neurology. The 11-year-old guidelines say, for example, that if an athlete’s concussion symptoms, such as dizziness or nausea, last longer than 15 minutes, he should be benched until he’s been symptom-free for a week. The most startling data point–uncovered by the same researchers who in 2007 brought to light the fact that girls have a higher incidence of concussion than boys–is that 16% of high school football players who lost consciousness during a concussion returned to the field the same day. The consequences of going back early can be dire. Last September, Jaquan Waller, 16, suffered a concussion during football practice at J.H. Rose High School in Greenville, N.C. A certified athletic trainer educated in concussion management wasn’t onsite, and the school’s first responder who examined Waller cleared him to play in a game two days later. During that game, Waller was tackled. Moments later, he collapsed on the sidelines. He died the next day. A medical examiner determined Waller died from what is called second-impact syndrome, noting that “neither impact would have been sufficient to cause death in the absence of the other impact.” Research indicates that younger, less developed brains are at greater risk of second-impact syndrome, which is why the new concussion study from the Center for Injury Research and Policy at Nationwide Children’s Hospital in Columbus, Ohio, is so troubling. Submitted to a scientific journal for peer review, the yet-to-be-published study examined 1,308 concussion incidents reported by athletic trainers and found that in girls’ volleyball and boys’ basketball and baseball, more than half of concussed players returned to play too soon. “These levels are way too high,” says Dawn Comstock, an Ohio State pediatrics professor and co-author of the new study. She cites several factors that are driving the numbers. Not enough high schools have certified trainers who know how to deal with concussions–just 42% do, according to the National Athletic Trainers’ Association. In some instances, overcompetitive coaches, who are not required to be trained in concussion management, are pushing players back onto the field. And too often the players themselves aren’t reporting head trauma, with team spirit giving them too much of a warrior mentality. See pictures of eighth-graders being recruited for college basketball. See pictures of a diverse group of American teens.