Girls who have symptoms of back pain after waking up from a nap may be caused by the following reasons: First, it may be caused by overexertion. Some girls who have not exercised for a long time will cause muscle weakness in the lower back. Such patients who do excessive activities involving the waist, such as prolonged standing or related physical exercise, will often wake up the next day with a significant soreness and weakness of the waist. In addition to this, if a woman grows to work or study sitting or standing for a long time, it is easy to cause lumbar muscle strain, resulting in the symptoms of lumbar pain after waking up. Secondly, it may be caused by a bed that is too soft. Some girls tend to make their beds very soft, which tends to make the patient sleep with some bad physiological curvature of the lumbar spine. The muscles around the lumbar spine are prone to spasm, which in turn causes the above symptoms. Thirdly, it is also common for girls to have cold conditions in the lumbar region during night sleep, leading to sterile inflammation here, which can also cause the above symptoms.