There are many reasons why children get leg cramps at night, such as lack of calcium, cold and excessive exercise. 1. Calcium deficiency: the child is in the stage of rapid physical development, so the body needs the nutrient demand is also higher, if the child usually like picky eating and partiality, resulting in calcium content intake is too low, thus causing the body calcium deficiency phenomenon. This can lead to discomfort such as difficulty in falling asleep and leg cramps at night. 2. Cold: When sleeping at night, the child is not covered properly, especially in winter, the room temperature is relatively low, resulting in cold legs. This can also cause localized muscle spasms, which can lead to leg cramps. 3. Excessive exercise: children are generally more active, if the daytime, a large number of strenuous exercise, resulting in excessive leg muscle movement, there can be spasms and lactic acid buildup phenomenon, resulting in leg cramps and soreness and other discomforts. When a child has leg cramps at night, it is important to identify the cause of the problem in a timely manner and deal with it accordingly.