The baby’s head shaking from side to side during sleep may be a normal physiological phenomenon, or it may be due to eczema or calcium deficiency. 1. Physiological phenomenon: due to the baby’s age, the development of the nervous system is not perfect, may cause the head or limbs shaking around when asleep, this is a normal physiological phenomenon, parents do not need to worry too much. 2. Eczema: baby skin is more delicate, the environment is hot, easy to cause eczema, which appears itchy skin, rash. When the baby eczema occurs in the head, pillow and skin friction, will cause the head skin discomfort aggravated, thus appearing head shaking the situation. 3. Calcium deficiency: baby lack of calcium and other substances will cause symptoms of mental excitement, and in severe cases may lead to rickets. Calcium deficiency can cause babies to wake up easily, sleep uneasily, and sweat more during sleep, thus causing babies to shake their heads and sweat while sleeping. There may also be other reasons why your baby swings his head from side to side while sleeping.