1. Why do babies cry at night and not sleep? It is very common for babies to cry and not sleep at night. This can be caused by a number of factors: loss of appetite, gas, over-excitability, etc. In addition, there are some physiological reasons: tooth growth and fever, etc. 2. How to help babies fall asleep? For babies who cry and can’t sleep at night, parents can take the following measures to help them fall asleep: 1. Establish a regular schedule