If a newborn baby laughs while sleeping, it is mainly considered to be caused by the following two reasons. First, it is caused by a normal physiological condition. In this case, the child will sometimes dream during sleep, and involuntary laughter in this case is a normal phenomenon. After the child wakes up, the mental state is better, eating is normal, growth and development is also normal, weight gain is also normal, parents do not need to worry too much. Secondly, it is caused by pathological factors. The pathological factors that cause children to sleep and laugh are mainly due to epilepsy. Parents can take the child to the neurology department of the children’s hospital for an EEG. If there are epileptic waves in the EEG, the condition is diagnosed as being caused by epilepsy. Parents should promptly apply anti-epileptic drugs to control the child, and may consider applying sodium valproate oral solution.