The sudden shaking of the body when sleeping is more common, caused by the following main causes: 1, if the rest of the nightmare, when frightened can appear sudden body shaking, is a normal physiological phenomenon, without treatment. 2, low calcium twitch, calcium ions mainly to maintain muscle excitability, if the blood calcium ions low can appear muscle spasms, limb shaking. The symptoms of calcium deficiency can easily occur in the elderly. 3, during sleep, if the room temperature is too low can also cause the symptoms of body shaking, usually do not give yourself too much psychological pressure, do not stay up late, if there are symptoms of calcium deficiency, appropriate calcium supplement and strengthen nutrition.