The boyfriend takes Emergen-C every day and (knock on wood) is NEVER sick. Even if he does start feeling the sniffles coming on, he'll double up and it will be gone the next day. I can't take it because the fizziness makes me nauseous. But I agree that a lot of the problem is sleep. I'm currently fighting travel induced bronchitis so I know what you mean. Had it a month ago and despite antibiotics, it came back after a solid month on the road. My doc put me on bed rest and luckily no travel planned for this week.