Five-month-old babies sleep a lot during the day and sleep late at night is a manifestation of biological clock disorder, which may cause sleep disorders, endocrine disorders and other conditions, thus affecting the development of the baby. Biological clock disorders can lead to five-month-old babies can not sleep normally at night, causing insomnia, difficulty in falling asleep and other sleep disorders, which may affect the baby’s appetite, mental status, etc., but also may cause the phenomenon of decreased immunity. Baby’s growth hormone secretion is generally at night, and growth hormone plays an important role in the growth and development of babies, the time of day growth hormone secretion is not balanced, the amount secreted at night during sleep is higher than the daytime, if the baby’s biological clock disorders may cause endocrine disorders, thus affecting the growth and development of babies.