Calf muscle cramps in the middle of the night while sleeping may be seen in the following conditions: First, the most common in clinical practice is due to lumbar disc herniation. The herniated disc compresses or stimulates the nerve roots causing radiating pain or cramp-like pain in the muscles of the innervated area. The most common clinical condition is a herniated disc in lumbar 4, lumbar 5, or lumbar 5, sacral 1, which compresses the nerve root in lumbar 5 or sacral 1, respectively, resulting in cramping in the posterior region of the lower leg. In this case, it is necessary to improve the lumbar spine CT or MRI examination in time to further clarify the diagnosis, and then take corresponding treatment measures. Secondly, the cramps may be caused by local tumors. Because the tumor stimulates the surrounding muscles or fascia, muscle spasm occurs, which is also known as cramping. In this case, it is recommended to improve the blood test and local imaging examination, and once the tumor is confirmed, timely treatment should be carried out.