Short-term effects of feed composition on sleeping and crying in newborns

To determine whether the composition of feedings would affect newborn behavior independently of the act of feeding itself, 53 two- to three-day-old normal newborns were randomly assigned to receive an extra feeding of water, carbohydrate (lactose), or balanced formula 3 hours after their usual early morning feeding. Previous studies in adult humans and animals, and a single study in human newborns, have indicated that more sleep might be expected following the carbohydrate feed compared with the water and balanced-formula feeds because of recruitment of centrally mediated serotonergic systems. Behavioral effects were assessed for 40 minutes postfeeding by direct observation of the newborn's states (quiet, active, and indeterminate sleep; drowsiness; non-cry wakefulness; and fret/cry). Feed composition did affect behavior, and the effects were fairly specific to particular newborn states. Non-cry wakefulness and drowsiness were unrelated to the presence or type of nutrients, but they tended to occur soon after the meal in all groups. Crying was increased in water-fed newborns relative to both carbohydrate- and formula-fed newborns. Sleeping showed specific patterns of change in all three groups. Sleep duration was increased in the balanced-formula group compared with the water group throughout the observation period. Contrary to the prediction, sleeping duration in carbohydrate-fed newborns never exceeded that of formula-fed newborns; rather, it resembled that of water-fed newborns early in the postprandial period, but formula-fed newborns later. These effects could not easily be explained by potential confounding factors such as handling, volume ingested, caloric intake, or plasma glucose concentration.(ABSTRACT TRUNCATED AT 250 WORDS)