A 1.5 year old baby crying in his sleep may be due to physiological reasons, dietary reasons, rickets and other reasons. If the 1.5 year old baby is covered with too much or too little bedding, the room temperature is too low or too high, or the child wants to defecate and urinate, and a series of other causes that will cause the child to be uncomfortable may cause the child to cry. In terms of diet, if your child eats too little, he or she may wake up hungry and cry during sleep, while if your child eats too much food before going to bed, he or she may suffer from gastrointestinal discomforts such as food retention, abdominal pain, and so on, which may cause crying. If the child lacks vitamin D and calcium leading to rickets, may also have the symptoms of crying at night, usually accompanied by occipital baldness, excessive sweating, square skull and so on. 1.5 year old baby sleep old crying may also have other reasons, it is recommended to go to the hospital, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.