There are several common causes of morning leg cramps: 1, cold. Because the morning temperature is the lowest in the day, and low temperature is easy to stimulate muscle cramps, that is, cramps; 2, inappropriate activities. It is common at the beginning of the morning exercise, the body joints are stiff in the morning, in the event that there is no warm-up exercise before the activity is prone to lower limb muscle cramps. 3, calcium deficiency. It is common in the elderly, because the loss of calcium in the body is more serious, long-term low calcium state is likely to cause lower limb cramps. 4, long-term strenuous exercise. The muscle is in a state of long-term tension, the large amount of acid produced can not be metabolized in a timely manner, and the acid repeatedly stimulates the muscle, easy to cause spasms cramps. 5, inappropriate posture. Long squatting and sitting, prolonged squatting and sitting stuck pressure on blood vessels, resulting in blood flow disorders, ischemia and hypoxia can also cause muscle spasms and cramps.