For the symptoms of leg cramps in the middle of the night, it is mainly seen in three reasons, as follows: First, calcium deficiency, especially in the growth period of adolescents, if they do not have a good supplement of calcium, or the middle-aged and elderly people have an abnormal loss of calcium in the body, it will lead to leg muscle cramps, and this condition will appear at night when sleeping with leg cramps. Second, seen in the leg muscle strain, such as those engaged in heavy physical labor or athletes, but after a long time during the day leg muscle overstress, strain, rest at night, muscle spasm, this situation will also appear in the second half of the night leg cramps symptoms. Third, see in the cold, especially in the second half of the night the weather is cooler, if not well protected legs, this situation in the cool air invasion, it is easy to lead to excessive contraction of the leg muscles, thus causing the symptoms of cramps.