No physical activity for three weeks.At 3 weeks, you can walk on a treadmill or ride a stationary bike.At two months, you can resume all physical activity with a sports bra.No lying on your side for two months.For more information on post-op care, please read my book, "Cosmetic Breast Surgery - a complete guide from A to double D".
You can usually sleep on back or side to side anytime after reduction but you don' t want to sleep Immediately afterward on your stomach,it can be painful, run the risk of popping stitches and some surgeons think it can mesh up the contours if compressed and squeezed early on.I suggest wait about a month assuming healing is normal