Sleeping on the back will reduce the risks of damaging your nose. You should put a pillow or two under your head to keep your head elevated to a 45-degree angle as sleeping upright can help you reduce swelling in less time.
Add some pillows around you when you sleep to prevent your body from rolling during your sleep. You can also add some pillows under the legs to reduce back pain.
If you are not used to sleep on your back and you wonder “How many days should I sleep on the back after rhinoplasty?” then you must know that the period you should sleep on your back is about a week at least. However, check with your surgeon because he/she is the one who knows exactly the appropriate period for your specific case.
Sleeping on the back is probably the best sleeping position after nose surgery.