The rotator cuff is a group of 4 muscles which helps to stabilise and go the shoulder joint. Rotator cuff accidents can vary from shoulder impingement/ tendinitis to partial or entire tears. Keep your excess weight off of the influenced shoulder after you slumber by lying on your other side. https://www.theorthopaedicandpainpractice.com/is-my-shoulder-pain-caused-by-a-rotator-cuff-tear/