Four-month-old baby sleep less, may be the environment, hunger and other physiological factors, but also may be functional dyspepsia, rickets and other diseases caused by acute gastroenteritis and other diseases. 1. Physiological factors: If the sleeping environment in which the four-month-old baby is placed is too bright or the temperature is not suitable for sleeping, it will affect the baby’s sleep and lead to the phenomenon of little sleep. It is also possible that parents do not feed their babies enough, and the baby will be hungry, which will also lead to the phenomenon of less sleep. 2. Functional dyspepsia: Functional dyspepsia is caused by a combination of factors, such as the local environment in the stomach, the sensitivity of the internal organs and so on. Children with functional dyspepsia may experience a feeling of fullness, epigastric discomfort, loss of appetite, insomnia, belching (burping) and other symptoms. In addition, children with functional dyspepsia may also experience nausea, vomiting and other symptoms. 3. Rickets: rickets is caused by vitamin D deficiency, the main symptoms of children with excessive sweating, irritability, restless sleep at night, often wake up. 4. other: acute gastroenteritis, cerebral palsy and other diseases can also lead to the phenomenon of four-month-old baby sleep less. Four-month-old babies sleep less, there may also be other reasons, it is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.