The pain in the middle of the back can be caused by various factors, which can be seen in the improper sleeping posture and other life factors, but also in the ligament strain, lumbar disc herniation and other diseases. 1. Improper sleeping position: when the bed is too hard and the sleeping position is improper, it may lead to pain in the middle of the back of the waist. 2. Ligament strain: When bending too much or exercising in an improper posture, it can lead to injury of lumbar ligaments such as the supraspinous ligament, which can lead to ligament strain. At this time, it can be manifested as pain and swelling in the affected area of the waist. 3. Lumbar disc herniation: it is a common spinal surgery disease, which can be caused by overwork, heredity and other factors. The main symptoms can be seen as pain in the lumbar region, sciatica, lower limb pain and numbness. There may also be many reasons for the pain in the middle of the back of the lumbar back, after excluding physiological reasons should promptly go to the hospital, hospital-related examinations, in order to clarify the cause of the disease, and actively cooperate with the doctor’s treatment.