Many theories are thrown around to explain the rise in the diagnosis and treatment of A.D.H.D. in children and adults. According to the Centers for Disease Control and Prevention, 11 percent of school-age children have now received a diagnosis of the condition. I don't doubt that many people do, in fact, have A.D.H.D.; I regularly diagnose and treat it in adults. But what if a substantial proportion of cases are really sleep disorders in disguise?