Hello and thank you for your question. Each surgeon has their own thought process around the need (or not) to wear a bra post op. I would recommend that you ask your Plastic Surgeon for his/her recommendation. That being said, I see little benefit to wearing a bra at night at 3 months post op. Some patients do feel more comfortable wearing a bra at night, and if you do, that is perfectly acceptable.
This is a question to be addressed to your own surgeon. I personally don't see any benefit in wearing the bra at night.