The reasons why babies are prone to fever at night are as follows: 1. The baby’s cerebral cortex is attracted to various living foods and activities of interest during the day, when the body secretes relevant hormones, the immune system is active, the nervous system is hyperactive, the body’s organs and systems are operating effectively, and the pathogens of infection can be effectively suppressed. At night, after the baby falls asleep, the brain is in a resting state, the functions of all organs of the body are relatively reduced, the pathogens inhibited during the day are lifted, the pathogens begin to replicate in large quantities, producing inflammation, so the phenomenon of fever appears. 2, compared to the day, the baby does not drink as much water during the night during sleep, the lack of water is also the reason why babies are prone to fever at night. 3, the baby’s mild fever will not affect play and appetite. Parents look at the baby’s spirit is fine, so they do not care, and will not measure the temperature, so at night the symptoms of high fever easily appear.