Anemia in 3-month-old infants usually does not affect sleep, and poor sleep in infants may be caused by insufficient milk, lack of calcium and other reasons and so on. Anemia in infants is mainly manifested by pale skin and mucous membranes, loss of appetite, abdominal distension, constipation, nausea, mental instability, emotional irritability, etc., but it does not have much effect on sleep. Poor sleep in 3-month-old infants is related to insufficient milk, if the infant is not full, the number of times of eating will be more frequent, thus affecting sleep; infants lack of calcium will cause increased excitability of the cerebral vegetative nerves, which will also affect sleep. 3-month-old infants with poor performance should seek timely medical attention to clarify the cause and carry out targeted treatment, so as not to affect the healthy development of infants.