What are the disadvantages of wearing bra at night while sleeping?

None.: It may not be as comfortable as sleeping without a bra, but there are no disadvantages of sleeping with a bra on. If you are having breast pain that is relieved with additional support, then go ahead and wear a bra. Most women are comfortable sleeping with just a t-shirt. If you are breast-feeding, it may be much more comfortable to wear a bra, but look for one without an underwire!

Proper cup size: Some women (especially those with larger breasts or who are pregnant) sleep in a bra for comfort. It is recommended that a bra worn for sleep have a soft cup without underwire or metal clasps. A shelf or cross-over design is also recommended. Bras worn for sleep are made. Use of improper cup depth can lead to rashes or chafing (due to breast contact against chest wall w trapped sweat).