Sleep patterns of infants in the first year of life.

A prospective study of 132 infants aged from 1 month to 1 year found that infants who were breast fed or breast plus bottle fed were significantly more likely to wake at night throughout the first year. Social class of the family, parity of the mother, and the weight gain of the infant had no consistent effects. This increased waking was not due to mothers of wakeful infants prolonging breast feeding to soothe their infants.