Three and a half year old children fall asleep and talk nonsense, may be related to the daytime play too tired, may also be due to shock, sleepwalking and other reasons. 1. daytime play is too tired: three and a half year old children in the daytime if the amount of activity is too large, play too tired, or daytime play is too excited, resulting in increased excitability of the cerebral cortex, resulting in the night after falling asleep, the cerebral cortex is still in the state of excitability, there may be sleep sleep talking, the phenomenon of talking nonsense. 2. Being frightened: three and a half year old children’s brain nervous system development is still immature, if during the day due to some adverse events stimulation, resulting in being frightened, resulting in a high degree of cerebral nervous tension, may lead to the phenomenon of talking nonsense after falling asleep at night. 3. Sleepwalking: mainly manifested as awakening from sleep, but incomplete awakening, going out to wander, cleaning, etc. in a half-awake state, and the phenomenon of talking nonsense may also occur. The cause of the disease is not yet clear, and it is mostly considered that it may be related to genetic factors, overwork, mental overstress and other factors. Three and a half year old children fall asleep talking nonsense, may also be caused by other reasons, if the symptoms of frequent recurrence, or the presence of other discomfort, it is recommended to seek medical attention as soon as possible.