Sleeping pressure on the arm, feel very painful, may be due to the following reasons: 1, there may be an inadvertent injury to the arm, such as the patient’s activities during the day, may inadvertently caused by the impact or twisting, and then in this part of the contusion or slight fracture situation. While the patient may not feel the pain caused by this injury during other activities during the day, the pain may become very obvious during sleep at night when the area is compressed or pulled by a particular body position. In addition, if there is a puncture injury in the upper limb, such as a foreign body left in the body, may also produce similar symptoms. 2, this situation may be due to the infected foci of this area, such as in the upper limb of the subcutaneous cellulitis, may also lead to similar symptoms. 3, this situation may also be due to the patient’s fatigue.