Small arm pain in the morning may be caused by cervical spondylosis, poor sleeping posture, vascular lesions and so on. 1. Cervical spondylosis: acute attack of cervical spondylosis will stimulate the nerve root to cause acute edema of the nerve root, resulting in clinical symptoms of arm pain when getting up in the morning, which can also be accompanied by neck pain, restricted movement and other symptoms. 2. Poor sleeping posture: incorrect sleeping posture at night, so that the arm is under pressure for a long time, the muscles are in a spasm, stiffness, will appear in the morning when you wake up arm pain. 3. Vascular lesions: when there are varicose veins in the arm, blood vessel stenosis, occlusion, etc., due to the reduction of limb activity or pressure at night, which can lead to a reduction in the blood supply to the arm, resulting in arm pain when getting up in the morning. Wake up in the morning arm pain may also be caused by other diseases, it is recommended to go to the hospital in a timely manner to improve the auxiliary examination, after a clear diagnosis for targeted treatment.