Linnea Sorensen falls into a funk whenever her girlfriend of four years leaves for her six-month stints with the Marines, and the high school junior has trouble concentrating on her classwork.
"I'm somebody who struggles with my mental health quite a bit," said the 17-year-old, who attends school in Schaumburg, Ill., a suburb of about 77,000 people northwest of Chicago. "When you're in school and not fully mentally there, it's like you're not really grasping anything anyway."
