In most cases, the baby sleep suddenly shaking may belong to the normal phenomenon, may also be caused by calcium deficiency, the former does not require special treatment, calcium deficiency caused by the recommendation of timely supplementation of calcium as prescribed by the doctor. 1. Normal phenomenon: the baby’s nerve is not yet fully developed, so when sleeping, there will still be part of the brain cells in the state of excitement, and then appear to sleep suddenly shaking. Secondly, sleep myoclonus can also cause this phenomenon, if the attack is not frequent, usually do not need special treatment. 2. Calcium deficiency: Calcium deficiency will lead to the continued increase of nerve excitability after the baby sleeps, which will easily cause occasional twitching of the limbs. It is recommended to take your baby to the hospital for blood vitamin D test and blood calcium concentration test. Vitamin D supplementation can be given when necessary, and it is recommended to use it under the guidance of healthcare professionals to avoid side effects on the stomach and intestines. Babies with abnormalities should go to the hospital in time for examination, do not take a chance.