If you feel arm pain at night, there are usually several factors as follows: 1. The most common factors are orthopedic diseases, such as cervical spondylosis, frozen shoulder and neck and shoulder joint pain, all of which will cause clinical symptoms and performance of arm pain when sleeping at night. 2. The body will also release certain inflammatory mediators in the body. The inflammatory mediators, such as leukotrienes, bradykinin and prostacyclin, can lead to arm pain. 3, such as excessive exercise during the day or incorrect exercise methods, resulting in excessive metabolism of lactic acid in the body. The accumulation of lactic acid in the arms can also lead to arm pain. 4, such as drug-related rhabdomyolysis or rhabdomyolysis caused by sports strain, can also cause clinical symptoms of arm pain at night when sleeping.