The main causes of leg cramps at night are related to poor sleeping posture, cold at night, lack of calcium or overwork during the day. 1. Poor sleeping posture: If you don’t choose the right posture when you sleep at night, your leg muscles will be continuously stretched, which will easily lead to leg cramps. 2. Cold at night: If you don’t pay attention to keep your legs warm at night, it will affect your blood circulation when you are exposed to cold stimulation for a long time, which will lead to the symptoms of leg cramps at night. 3. Calcium deficiency: when there is a calcium deficiency in the body, if the situation is more serious, resulting in a lack of calcium ions in the blood, which can easily affect the nerve signal conduction, and thus produce leg cramps at night when you sleep. 4. Excessive daytime fatigue: during the day, if you have a long time of strenuous exercise or weight-bearing labor, frequent contraction of the leg muscles, it is easy to produce excessive fatigue, so it is easy to trigger the phenomenon of leg cramps in the night time when you go to sleep. If the phenomenon of leg cramps is more frequent, you need to consult a doctor, as soon as possible to clarify the cause, and under the guidance of a professional physician targeted treatment, so as to avoid injury or affect the quality of sleep.