Muscle spasms, also known as cramps, are spontaneous, compulsive muscle contractions that occur most commonly in the calves and toes. The pain can last from a few seconds to tens of seconds, especially in the middle of the night when the cramp can be painful to wake up. The main causes of leg cramps are divided into the following categories. First, systemic factors, high fever, epilepsy, tetanus, rabies, and calcium deficiency can cause the promotion. Second, common local causes, such as non-permanent cramps, often caused by strenuous exercise and when working fatigue, appear after rest. Poor sleep posture can also lead to muscle spasms, such as prolonged supine lying, so that the quilt pressed against the foot, or prolonged prone lying, so that the surface of the foot against the bed, can cause this condition. In addition, fatigue, lack of sleep and too much rest can lead to this condition, mainly due to the accumulation of local acidic metabolites that cause muscle spasm, and should enhance the discharge of carbon dioxide to prevent the accumulation of lactic acid, which can reduce the occurrence of this complication. In addition, cold stimulation, such as winter or sleeping with the blanket not covering the legs, may also cause muscle spasms.