There are several possible causes of arm swelling pain in the middle of the night: first, myofasciitis, myofasciitis patients often have pain on the inside of the scapula as the first symptom, which can radiate to the ipsilateral upper limb, especially at night when the arm swelling pain is very obvious, it is necessary to carry out relevant physical examination and examination to exclude other diseases for diagnosis; second, cervical spondylosis, cervical spondylosis can also appear when the nerve roots are compressed on one side of the arm swelling pain Third, peripheral nerve compression, if the peripheral nerve is compressed at the travel area, such as inflammation, tumor or traumatic adhesions, the symptom of arm swelling and pain in the middle of the night can occur, then we should The diagnosis and treatment should be carried out with relevant physical examination and electromyography.