The common causes of leg cramps during sleep include cold legs during sleep, calcium deficiency, fatigue and blood circulation disorders in the legs, etc. For specific cases, it is recommended to go to the hospital for a complete examination in order to clarify the causes. 1. Cold legs: In the process of sleeping, if the environment is cold and chilled, it will easily lead to the contraction of leg muscles and blood vessels, which can lead to muscle cramps in the legs. 2. Calcium deficiency: the reduced level of calcium ions in the blood due to various reasons can lead to increased excitability of the nerves of the leg muscles, which can lead to symptoms of cramps during sleep. 3. Fatigue: Before going to bed, due to long-distance walking, weight-bearing, etc., can lead to fatigue of the leg muscles, and then lactic acid and other metabolites accumulate in the leg muscles, stimulating the leg muscles can lead to cramps. 4. Blood circulation disorders: mostly seen in the sleep process, due to improper posture, resulting in a long period of leg pressure, venous blood reflux is not smooth, can lead to leg muscle cramps. Sleeping leg cramps recommend that patients seek medical attention in a timely manner, improve the auxiliary examination, in order to clarify the cause of the disease, by a professional physician for treatment.