Usually, 3-month-old babies sleep for about 14-15 hours a day. Parents need to realize that baby’s sleep is very important because most of baby’s growth and development is done in sleep, 70% of growth hormone is produced in deep sleep, and in addition sleep will secrete a lot of various hormones to maintain growth and development and normal metabolism. However, if the baby has a long sleep and at the same time has a poor diet or mental state, and the weight gain is not ideal, or even appears irritable or depressed state, it is definitely an abnormal phenomenon, parents need to immediately take the baby to the pediatric department of the hospital for a detailed examination to clarify the diagnosis and timely symptomatic treatment. In addition, parents should pay attention to the baby to develop good sleep habits, to start teaching the baby to distinguish between day and night when the baby is 2 weeks old, to avoid stimulating or frightening the baby.