Patients with fever at night and normal during the day may be caused by the following factors: 1) the patient may have a viral infection and may have a serious fever at night, but the temperature usually returns to normal during the day. If an infant has fever at night but normal during the day, it may be caused by accumulation of food, usually accompanied by anorexia, bloating, constipation and other symptoms; 3. Since there are many factors that can lead to the above symptoms, patients should go to the hospital in a timely manner, undergo relevant examinations to clarify the cause, and carry out relevant treatment for the cause.