Most Helpful Girl
There is no definate link between wearing a bra to bed and breast cancer.
However, if you wear a bra to bed, it's advised to not wear it in the day. Your breast tissue gets used be being supported and the muscles then hold them like that - if you take your bra after say 18 hours and look at your breasts, they are much more perky.
I don't wear one to bed, I find it more comfortable not to. Sleeping with it on you can roll over end up with pinchy, wirey, uncomfortableness!
It's a personal thing though. You get used to whatever. I think most women find it easier to not wear one at night and wear one in the day instead. It's probably considered more "normal"
If you do wear a bra to bed, it's normally advised not to wear a push up or anything cause obviously the position you lie in might affect the breast tissue.
I'm also gonna add, EVERYTHING gives you cancer according to this world. I read an article recently that said oxygen gives you cancer, too much water gives you cancer, not enough water gives you cancer, etc etc. Try not to get too worried about stuff but it's worth asking :)