A two-year-old baby who cries all the time at night may be caused by environmental factors, calcium deficiency, indigestion and so on. 1. environmental factors: if the baby sleep environment is too noisy or indoor light problems, will affect the baby’s sleep, resulting in poor sleep quality and always crying. 2. Calcium deficiency: due to the rapid growth and development of babies, it is easy to have a calcium deficiency phenomenon, once the calcium deficiency, it is easy to lead to an increase in the excitability of the cerebral cortex, easy to sleep at night, sleep disturbance, frequent waking up at night, crying and other symptoms. 3. indigestion: if the baby too much food before going to bed at night, after going to bed, the intestinal peristalsis is slow, it is easy to have indigestion, leading to the baby uncomfortable and thus crying. The two-year-old baby sleeps at night always crying, there may be caused by other reasons, if the symptoms continue to be unrelieved, you should consult a doctor in a timely manner, after the cause is clear, cooperate with the doctor to take treatment.