Children sleep sweating hair all wet may be caused by physiological factors, lack of calcium and vitamin D, environmental factors and other reasons. 1. Physiological factors: the child’s ability to regulate body temperature is not perfect. At the same time, the metabolism is more vigorous, so children often appear in the case of sweating while sleeping, sweating increases will lead to hair soaked in sweat. 2. Lack of calcium and vitamin D: vitamin D can promote calcium absorption, metabolism, if the lack of vitamin D will cause calcium deficiency, and lack of calcium will cause sympathetic excitation, which will stimulate the secretion of the sweat glands, and therefore will be in the night time sweating. 3. Environmental factors: high ambient temperatures lead to indoor air is not smooth, will cause children to sleep breathing is not smooth, so easy to sweat in bed, may also be due to bedding is too thick caused. Children sleep sweating hair all wet, there may be other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, give targeted treatment or treatment.