There may be several reasons for right shoulder pain when sleeping: first, cervical spondylosis, when cervical spondylosis compresses the nerve roots, right shoulder pain can occur, if the posture of the neck is incorrect at night, it can lead to more obvious pressure on the nerve roots and thus obvious pain in the right shoulder. When the shoulder joint has rotator cuff tear or frozen shoulder, it can lead to shoulder pain at night, especially in patients with frozen shoulder, who can have obvious shoulder pain when sleeping at night. In myofasciitis, the first symptom is pain in the medial scapula, which can radiate to the ipsilateral shoulder and upper extremity, and the pain is very significant at night when sleeping under pressure.