Sleep is very important for babies, and good sleep is good for their growth and development. Parents sometimes find that their babies do not sleep soundly, always tossing and turning, waking up frequently throughout the night, or crying, making it impossible for the mother to sleep soundly. Babies who do not sleep well at night need parents to pay enough attention to find the cause and take relief measures to ensure that the baby sleeps well. There are many reasons why babies do not sleep soundly, and they are divided into external and internal factors. Extrinsic factors include hunger, lack of calcium, too hot, bloating, colic, wanting to pee, teething, too excited during the day or change of sleep environment, physical discomfort, etc. Intrinsic factors are the immature neurological development of the baby’s brain, which has not yet established a fixed schedule of work and rest. Babies with higher nervous system excitability tend to have later physiological maturity and are prone to sleep disturbances. A small number of babies with neurological disorders such as brain injury may experience restless sleep along with other symptoms. According to these reasons, take measures to promote calcium absorption by taking vitamin D supplements on time, and calcium supplements for babies with calcium deficiency; adjust the amount of nighttime milk to avoid nighttime hunger; sleep in a suitable temperature and quiet environment, do not cover too much, change diapers or diapers in a timely manner; and avoid babies getting too excited before bedtime. Some babies who do not sleep well at night need to be considered lactose intolerant or milk protein allergic, and those with other symptoms such as diarrhea should be treated accordingly such as taking lactase and changing special formula. For some babies who do not find a reason for their restless sleep and are crying, consider colic and try to take simethicone oil to relieve it.