Four-month-old babies always shake their heads from side to side when sleeping may be related to the living environment, may also be caused by eczema, lack of calcium and other factors, can be timely general treatment or medication. 1. living environment: four months baby sleep always shaking his head from side to side may be the temperature is too high, the baby sweats too much caused by head discomfort, resulting in the emergence of this symptom. May also be the environment is too noisy caused, do not worry too much, timely adjustment of the environment can be. 2. Eczema: If your baby has eczema on the head, there will be obvious itching symptoms, leading to the baby shaking his head while sleeping, you can follow the doctor’s instructions to use the appropriate medication to apply. 3. Calcium deficiency: If the baby’s body lacks calcium, may cause the nervous system excitability, which will appear this symptom, you can follow the doctor’s advice to the baby to take calcium gluconate oral solution and other drugs. Usually need to observe the baby’s physical condition, if there is an abnormal reaction, it is recommended to consult a doctor in time.