It's 4 a.m. and your baby's been crying -- and you've wanted to cry -- for three hours. You know this isn't a hungry or tired cry, so something has to be wrong. When crying episodes become chronic, it might be colic, which is more common than you think. "Colic is a factor in at least one out of 10 babies in my experience," says Brooklyn pediatrician Anatoly Belilovsky, M.D. Here's what you need to know about colic to help you and your baby through it.