Terra Ziporyn Snider of Severna Park, Maryland, still remembers how difficult it was for her son to wake up for his 7:17 a.m. first-period class when he was in high school. There were times he’d turn on the shower, then head back to bed while waiting for the water to warm up, only to fall back asleep. One morning, he made it out the door but didn’t get far: He backed the car into the garage door because he’d forgotten to open it.