Difficulty in sleeping may be caused by cold legs, too much exercise during the day, calcium deficiency and other reasons. 1. Cold legs: It is mostly due to the usual failure to take warm measures or kicking the quilt at night, resulting in cold legs and local blood vessel contraction, which may lead to the symptoms of difficult legs when sleeping. 2. Excessive daytime exercise: if the child runs and plays excessively during the day, it may lead to muscle strain in the legs or the accumulation of a large amount of lactic acid, which cannot be decomposed in time, thus causing the child to have difficulty in sleeping. 3. Calcium deficiency: the child is in the stage of growth and development, if the daily intake of calcium and so on can not meet the body growth needs, may lead to the child to sleep legs difficult situation. There may also be other reasons for children to have difficulty sleeping, such as growing pains, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.