Why Do I Have Shoulder Pain At Night?

The most common cause of shoulder pain is rotator cuff tendonitis.

The rotator cuff tendon is situated between two bones. When you are upright and active throughout the day, gravity pulls your arm down and relieves the impingement on the tendon. At night, gravity is no longer pulling the arm down. The tendon is pinched between the two bones, which causes pain. Over time, this process can lead to shoulder bursitis and even rotator cuff tear.