Wearing a bra to bed is perfectly okay for your health and breast health as well.
I've heard that wearing a bra to bed can cause breast cancer and prevent breast growth but that's just a myth and no harm will be done to yourself or your breast if you decide to sleep in a bra if you want too.
Some woman are more comfortable sleeping in a bra and it's okay to do so.
Personally for me I cannot sleep in a bra so I remove it and I even hate wearing bras during the daytime but have too.
If you want to wear your bra to bed then go right ahead it's not not gonna harm you.