The baby cries when it gets dark, considering that it is related to physiological factors, environmental factors, and may also be caused by various factors such as calcium deficiency. 1. Physiological factors, due to the baby is relatively small, relatively insecure, so the baby may appear to the darkness of the crying symptoms. 2. Environmental factors, the baby cried when it was dark may also be related to environmental factors, if the environment is too noisy or sleep in the process of light too bright may appear this symptom. 3. Calcium deficiency, if the baby’s body lacks calcium, it may lead to a more sensitive nerves, so the symptoms of crying when it gets dark. The baby cries when it is dark, there may be other reasons, it is recommended to go to the hospital in time to improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.