Last January, Lauren Barnathan, 31, didn’t realize what was happening when she tried to roll over in bed but couldn’t because her left side was limp. The Tampa, Florida, resident had always been fit and active, so the tell-tale signs she was experiencing didn’t add up in her mind for someone her age. As soon as her then-fiancé flipped on the bedside light, however, he knew exactly what was happening: Lauren was having a stroke. Adam Barnathan, 32, an emergency medicine doctor, recognized the facial droop, inability to use one side of her body, and slurred speech that he often...