Causes of leg pain in the middle of the night include physiologic and pathologic ones. If this symptom occurs in children, most of them are due to growing pains, which is a normal physiological phenomenon. Common pathological causes include cold, fatigue, lumbar disc herniation, bone tumor, varicose veins, lower limb joint lesions and so on. 1. Growing pains: there are many reasons for growing pains, which may be the pulling pain caused by the rapid growth of bones, or muscle aches and pains due to excessive metabolic products of tissues in the process of development. 2. Cold: Cold may cause muscle spasms, leading to pain. 3. Fatigue: Excessive activity during the day can cause a buildup of acidic metabolites, leading to muscle soreness. 4. Lumbar disc herniation: it may compress the sciatic nerve causing radiating pain in one or both lower limbs. 5. Bone tumor: malignant bone tumors are almost always characterized by local pain and night pain. 6. Varicose veins: the obstacle of blood return in the lower limbs can easily lead to leg pain. 7. Lower extremity joint lesions: can induce leg pain, more obvious at night, such as knee osteoarthritis. The cause of leg pain in the middle of the night may also be tibial inward curvature, lack of trace elements, trauma and so on. Physiological middle-of-the-night leg pain does not need special treatment, patients do not need to worry too much. After eliminating physiological factors, if the rest can not be relieved, it is recommended to go to a regular hospital in a timely manner, by the doctor to clarify the cause of the disease, to give targeted treatment.