Difficulty in falling asleep in small children may be related to physiological factors, or may be caused by indigestion, rickets and other reasons. 1. Physiological factors: for example, children watching stimulating cartoons before going to bed, or excessive running and jumping before going to bed, playing too excited, etc., may lead to children’s cerebral cortex excitability, thus causing difficulty in falling asleep. 2. Indigestion: for example, children overeat, eat a lot of cold, indigestible food, easy to lead to indigestion, causing bloating, abdominal pain and other gastrointestinal discomforts, which may cause difficulty in falling asleep. 3. Rickets: If the child is severely deficient in vitamin D and calcium, rickets is induced, resulting in increased nerve excitability, it may cause difficulty in falling asleep, but also can be accompanied by dreamy sleep and easy to wake up, occipital baldness and other manifestations. Children have difficulty falling asleep, may also be caused by other reasons, exclude physiological factors, it is recommended to take the child to the doctor as soon as possible, after clarifying the cause, to give targeted treatment.