Dear lindie, Breast pain is a common breast symptom. The reason for breast pain is not clearly understood, and is not usually associated with breast cancer. Breast pain is sometimes associated with hormonal variations and is then called cyclical breast pain. Noncyclical breast pain does not seem to be linked to hormonal variations and is often localized to one area of the breast tissue. Noncyclical breast pain may or may not be the result of an injury to the breast.
Discuss your symptoms with your physician. Breast pain is evaluated based on the history of the pain you would give to the health care professional, as well as a physical examination. The need for further testing would be determined based on the above findings. Some recommendations for treatment of breast pain involve simple comfort measures such as a supportive or exercise bra, or application of warm or cold packs. Caffeine avoidance, limit salt intake and reduction of dietary fat may also help.
Sleeping with a sports bra would be more of an individual comfort/preference. It will not stunt the growth of the breasts, it may cause soreness if too tight.