The common causes of cramps at night are as follows: First, calcium deficiency: Mostly considered to be caused by calcium deficiency, calcium ions can inhibit the excitability of the neuromuscular junction. In children, it mostly manifests as hand and foot twitching and increased excitability of the nervous system, and children can manifest as crying and difficulty sleeping at night. And adults mostly manifest as muscle spasms and cramps in the calves and feet at night, often affecting normal sleep. In this case, it is important to go to the hospital early for testing and active calcium supplementation. Second, muscle strain: strenuous physical activity during the day, strain the leg muscles, at night there may be muscle protective spasm, contracture.