The causes of sudden shaking in sleep include physiological and pathological factors. Physiologic factors include excessive mental stress and localized exposure to cold. Pathologic factors include calcium deficiency, epilepsy and so on. 1. Physiological factors. (1) Excessive mental stress: when the mental stress is too great and the tension is too high, there may be a sudden shaking during sleep. (2) Localized cold: muscle spasms may occur when sleeping due to localized cold, resulting in sudden shaking during sleep. 2. Pathologic factors. (1) Calcium deficiency: when there is a lack of calcium in the body, it may cause muscle spasms, which may lead to sudden shaking during sleep. (2) Epilepsy: When neurons in the brain discharge abnormally, sudden shaking in sleep may occur. If you suffer from sudden shaking in your sleep frequently, it is recommended to go to the Neurology Department of the hospital in time to clarify the cause of the disease and then treat the symptoms to avoid delaying the disease.