Night waking in 4- to 8-month-old infants.

Parental reports of night waking and sleep patterns were obtained for 141 normal 4- to 8-month-old infants from middle-class families. A group of infants was identified who had a past history of colic and who were perceived to have a current night waking "problem." These infants awoke more often than other infants and also had significantly briefer total sleep duration. Night waking was described as a problem in infant boys more often than in infant girls. A second group of infants who awoke frequently was reported to snore or mouth breathe when asleep. This group of infants did not have a past history of colic, was not perceived to have a night waking problem, and was not overly represented by boys. Ordinal position, father's education level, gender, and method of feeding did not affect reported sleep patterns.