The child cries when he goes to sleep at night may be caused by physiological factors such as environmental discomfort and hunger, or it may be caused by indigestion, rickets and other diseases. 1. Physiological factors: If the indoor temperature is too low or too high at night, or if the child is in a hungry state, there will be a situation in which the child cries when he goes to sleep at night. 2. Indigestion: Due to the child’s young age, the development of gastrointestinal tract is not yet perfect. If the child eats too much food before bedtime, causing indigestion, abdominal pain, bloating and other abdominal discomfort will occur, which will also cause the child to cry. 3. Rickets: Rickets is a common pediatric disease, mainly caused by vitamin D deficiency. Children with rickets will have symptoms such as sleep disturbance and irritability, and will cry as soon as they go to sleep at night. There are more reasons for children to cry at night, it is recommended to take your child to the hospital for examination and clear diagnosis.