Children’s knee pain at night may be related to injury, inflammation, calcium deficiency and other reasons. 1. Injury: when children do not pay attention to protect themselves in the process of activities, there will be a fall or impact, which may cause damage to the knee area, resulting in children sleeping at night may appear knee pain performance. 2. Inflammation: when children’s knee parts appear (such as synovitis, arthritis, etc.) inflammation, due to the stimulation of inflammation, may lead to swelling of the knee, pain and other symptoms, resulting in children may appear at night when sleeping knee pain phenomenon. 3. Calcium deficiency: Because children need more calcium during growth and development, if there is a calcium deficiency, the development of bone and joints will be affected, leading to symptoms of knee discomfort when children sleep at night. When children sleep at night knee pain, it is recommended to go to the pediatrics or orthopedics, to clarify the cause of the disease, targeted treatment, as soon as possible to alleviate the symptoms.