Bra question!!! Please answer?

I'm 15 and I'm really slender and tall, my aren't very big I'm a size 34A and some of the girls at my school were talking in the locker room and they said that if you wear a bra to bed it will stunt your growth and make them hang low, they're pretty convinced on this. I always wear a bra to bed, not the underwire ones cuz those are uncomfortable to sleep in but my s to me don't appear to hang low and the problem is that I have 3 teenage brothers and theres my dad, I can't just run around with my pj's on in the morning and no bra. It would be pretty weird. So I really want to know, is this true?