The back stiffness in the morning may be caused by the following reasons: 1, may be the back at night when sleeping cold, resulting in poor blood circulation in the back muscles, local muscle spasm. The symptoms can be improved by applying warm compresses or activities. 2, it may be a mattress problem, such as the mattress is too soft or the bed board is too hard, the muscles on the back side must exert themselves for a long time when sleeping to maintain the correct posture of the thoracic spine, and the muscles contract for a long time leading to spasm. 3, it may accidentally cause misalignment of the small joints of the thoracic spine when sleeping, resulting in limited movement of the thoracic spine. Usually there is a very obvious pressure point in the middle of the thoracic vertebrae, and if the misalignment is more powerful, a very obvious misalignment of the spinous process will be felt. The symptoms are relieved immediately after the manual reset.