The common causes of numbness of the hands and legs are caused by temporary poor blood flow, cervical spondylosis, diabetes and so on. 1. Temporary poor blood flow: numbness of the hands and legs is more common in life, prolonged hand and leg pressure on blood vessels, so that blood flow is not smooth, there will be numbness of the hands and legs, appropriate activities of the limbs, numbness of the hands and legs after the symptoms can be relieved. 2. Cervical spondylosis: patients with poor posture in the office for a long time, resulting in degenerative changes in the cervical spine, spinal stenosis and ligament thickening and thus compression of the peripheral nerves, there will be numbness in the hands and legs. 3. Diabetes: If the blood sugar control of diabetes is not good, it is easy to have chronic complications of diabetes. The main manifestations are numbness of the hands and legs, heat, electric shock and other sensations. Clinical nerve irritation, neuritis, cerebral thrombosis, lumbar intervertebral disc herniation and so on will lead to the phenomenon of numbness of the hands and legs, the patient should consult a doctor in a timely manner, under the guidance of a professional doctor to clarify the cause of the correct treatment.