Hi, I have a 22 year old Son who works second shift in custodial at our local High School 1 mile away. When he came home for dinner as he does everynight, I noticed his lips were a slight bluish edge around them. I know he sleeps from about 2:00am to 12:00 daily. He doesn't each much, and sometimes goes to work without eating anything. He complained his stomach was bothering him, I said it was due to not eating, after he had dinner he felt better. What could cause this bluish dark edge around his lips?